My time frame was 5 hours, starting at 10am it had to be done by 3pm as I was heading out and would be out (ballroom dancing, ok I was having fun) until 10pm. As always I work by hand, so this had to be all hand stitched.
This is how the gown looked on the dummy at 10am. I had to take it down from a 43 bust to a 36 bust and a 37 waist to a 30.
The original bodice, sleeves and shoulder straps were discarded. I recut the back panel using the new pattern piece that I knew fit me. Cut new fronts and new sleeves also with the new pattern. I did not refit those pattern pieces, just cut and sewed. (My kitchen is a mess in the background, hey, you can sew or clean, can't do both!)
I sewed faster than usual and the stitches came out more like an 18th century original gown than I could have imagined.
A short lunch break and it was onto sleeves and reattaching the gown skirts.
I was able to reuse the robings and back neck facing which saved time and was finished by 3:01, with a 15 minute lunch break and multiple episodes of the X-Files. Ya gotta love Netflix for mindless background noise.
The new dummy was not only me wearing stays, but since it is entirely foam, I was able to pin directly into it, another huge time saver.
A quick pic with camera phone in the garden before jumping in the car. Very pleased with the fit, I love the fabric of this gown, it is light and cool to wear. An Indian cotton from Jo-Anns a zillion years ago.