I think three of my platys look pregnant. How long will it take for them to drop the fry? Also, should I use a fry trap, a nursery tank or an aquarium divider to separate them?

Platies are usually pregnant between 6 - 8 weeks. Once you notice that your platy's stomach has a \___/ shape, then you know she is due to give birth soon. Platys tend to stress out when you put them into a breeding trap, so small, separate 10-liter tanks might be better prior to the births.