i have transplanted 3 weeks into flower and they didnt even get shocked, what i do may be a bit ridiculous but i have done it several times and each time they kept growing as usual.

get a candle and light it, turn off all lights and have the pots already made up and simply turn the plant upside down and let her fall out very easily and place in new pots and cover up, if done very gently they wont even know it happened and they will continue to flower as normal.