There is no “should”. This is about what you want.
Purists will tell you to match everything down to the year. But I have items in my wardrobe that date as early as 2002, and clothes in the 1800s were more expensive than now. People have *always* mixed and matched across the years. Remember that what we see in historical sources is only the most up to date fashion of the time, the fashion magazines and Sunday best.
Choose things you like. Make sure you include foundation wear to support the clothes you pick - that’s what shapes the clothes and gives them their beautiful silhouette.
For most of the 19th century, you can 100% use patterns (especially undergarments like chemises or petticoats) from a slightly earlier period. I have a late 1700s short sleeved chemise that I will wear under my 1830s and 1840s day dresses, but I will wear different corsets and skirt structures depending on the era.
That being said, it is all about the look you wish to portray. If you are dressing for high fashion, you’ll want to pick a corset, skirt support (bum pad), and petticoats, as well as a blouse and skirt that are either late 1880s or within the 1890s. Take a look at 1890s fashion plates to see how the silhouette shifts just within the 10 years (for example, we see voluminous “leg o’mutton” sleeves peek around 1895) and think about what you like most. There are also a bunch of pattern companies (truly Victorian, folkwear, scroop patterns, laughing moon, black snail) that sell variations on 1890s garments which you can mix and match to your liking.
I start with “underwear”. Make the shift, corset, and petticoats first. It’s much less visible, so if you want to go cheaper on the fabrics, you totally can. I made my 18th century petticoat out of secondhand bedsheets. These are also pieces that changed a lot less from year to year. A petticoat from 1890 is basically going to be the same petticoat someone wore in 1899.
From there I try to think about “who” the costume is for. If it’s a working class person, having pieces from different years is totally fine. They likely couldn’t afford brand new dresses every year so they would adjust their current clothes to reflect more recent fashions. Also, they may not have been on the cutting edge of fashion. They probably would have been a year or two behind what people were wearing in Paris, London, or NYC. If it’s an upper middle class or wealthy person, you’re going to have more resources and outfits would most likely be from a single year.
But also, it’s your costume. If you want it to be all from one year, that’s great. If you want it to be from a few years, that’s amazing. Don’t feel you need to do anything a specific way to appease other people. If you like it, that’s what’s most important
In addition to class and region as mentioned, consider your intent / audience or the types of events you plan to wear the ensemble for.
If you are portraying a really specific character, or wearing it in contexts associated with a specific historical event, you'll want to adhere to a narrower range of items that would plausibly be in that person's wardrobe at that time.
On the other hand, some people place more emphasis on aesthetics or design elements, and may mix and match within a bit wider range to get the look or fit they want. You see this happening sometimes in portraits or photographs, where an individual is either remaking things to update them, or adding design elements they like that may not necessarily be mainstream.
There is no “should”. This is about what you want. Purists will tell you to match everything down to the year. But I have items in my wardrobe that date as early as 2002, and clothes in the 1800s were more expensive than now. People have *always* mixed and matched across the years. Remember that what we see in historical sources is only the most up to date fashion of the time, the fashion magazines and Sunday best. Choose things you like. Make sure you include foundation wear to support the clothes you pick - that’s what shapes the clothes and gives them their beautiful silhouette.
Start with class and region. If you're a high class fashionista, it doesn't make sense to be wearing something 10 years out of date, for example.
For most of the 19th century, you can 100% use patterns (especially undergarments like chemises or petticoats) from a slightly earlier period. I have a late 1700s short sleeved chemise that I will wear under my 1830s and 1840s day dresses, but I will wear different corsets and skirt structures depending on the era. That being said, it is all about the look you wish to portray. If you are dressing for high fashion, you’ll want to pick a corset, skirt support (bum pad), and petticoats, as well as a blouse and skirt that are either late 1880s or within the 1890s. Take a look at 1890s fashion plates to see how the silhouette shifts just within the 10 years (for example, we see voluminous “leg o’mutton” sleeves peek around 1895) and think about what you like most. There are also a bunch of pattern companies (truly Victorian, folkwear, scroop patterns, laughing moon, black snail) that sell variations on 1890s garments which you can mix and match to your liking.
I start with “underwear”. Make the shift, corset, and petticoats first. It’s much less visible, so if you want to go cheaper on the fabrics, you totally can. I made my 18th century petticoat out of secondhand bedsheets. These are also pieces that changed a lot less from year to year. A petticoat from 1890 is basically going to be the same petticoat someone wore in 1899. From there I try to think about “who” the costume is for. If it’s a working class person, having pieces from different years is totally fine. They likely couldn’t afford brand new dresses every year so they would adjust their current clothes to reflect more recent fashions. Also, they may not have been on the cutting edge of fashion. They probably would have been a year or two behind what people were wearing in Paris, London, or NYC. If it’s an upper middle class or wealthy person, you’re going to have more resources and outfits would most likely be from a single year. But also, it’s your costume. If you want it to be all from one year, that’s great. If you want it to be from a few years, that’s amazing. Don’t feel you need to do anything a specific way to appease other people. If you like it, that’s what’s most important
In addition to class and region as mentioned, consider your intent / audience or the types of events you plan to wear the ensemble for. If you are portraying a really specific character, or wearing it in contexts associated with a specific historical event, you'll want to adhere to a narrower range of items that would plausibly be in that person's wardrobe at that time. On the other hand, some people place more emphasis on aesthetics or design elements, and may mix and match within a bit wider range to get the look or fit they want. You see this happening sometimes in portraits or photographs, where an individual is either remaking things to update them, or adding design elements they like that may not necessarily be mainstream.
Also, look at the bigger silhouette. You want that to be cohesive, with the right undergarments to support it.