Hi scoucerlad...not really a lot of dateable details in the lady's dress...not sure about the sleeves but I'd suggest the slight beginning of the puffy shoulder here, so I'm guessing about 1889 or so.
I'd really like to see the back if possible...could you reduce the file until it's below the 500kb limit and post it, please? As it's just a back and not for restoration, it doesn't have to be very large...
Cheers,
China