Sorry misread what you wrote, thought you were doing an animation :D

But if its not an animation and you are using conforming cloth and the change of cloth is happening off camera, why does the number of frames then matter? don't really understand that. But you could maybe just change the scale of outfit A to 0 at frame 44 that should make it so small that you can't see it and then you scale outfit B into the correct scale at frame 55.