Well I believe that normal gestation period for a platy is somewhere between 28 and 32 days. It's always had to give an exact eta as it is hard to know exactly when she was impregnated unless you have CCTV on her. She looks a little way off yet...not fit to burst. With mine I normally find that the hide in the planting 3-4 days before dropping. Also some say that when a white spot become visable near her backside then a drop is about a day away - I've never experienced this though. A change in behaviour, mood swings, a wee bit of aggression etc etc etc could all be signs she is close. Best advice - keep an eye on her behaviour and watch her get bigger! I'm sure others have experiences of platy pregnancy to add.