Platys normally have fry every 4-6 weeks, yours look pretty plump but not squared off yet. You'll notice their belly look kinda like this from the side \____/ the bottom will be like flat, once that happens its only a matter of a couple days.
IMO/E those plastic traps stress the fish out the less time they have in there the better. I use a tank divider that way she can have room to move around and not stress and the fry have their own little habitat where the bigger fish can't get them.