It depends on how im feeling weather i use molasses or not,when i do use molasses in a grow i feed the plants right up until their last watering,im not a proponent of flushing weed as i cant see any real scientific reason to do so,nor is there any proof posted anywhere on the internet that flushing is a needed pratice,most information regarding this pratice traces back to hydro fertilizer companies who just so happen to sell expensive products for flushing.
Ive done a few roughly handled experiments using flushed & non flushed plants with other smokers as the test subjects,i tried my best to make sure that the people smoking had no information that could bias their feedback comments,not one person could point out any differences between flushed & non flushed so i gave up flushing & filed it away as a wives tale.
Anyhow if your the type who wants to be better safe then sorry then stop using molasses,i cant taste any differences in buds grown with molasses but ive seen how the buds absorb the molasses & hold it within the bud after harvest.