If I catch my Guppy having her fry I pop her into a trap, its quite obvious as the becomes very still and sometimes chills out on the heater. If I dont trap her nearly all of the fry get eaten, and she eats them. So I have to encourage the fry to swim into the bottom of the trap my disturing the water near them.
My swordtail I never catch dropping her fry,she always does it at night, she swims eratically to avoid being harassed by the male fish. I know when she is going to have them, but if I trap her she jumps out.
My Molly, just drops them when behaving normal.
So you can see different fish behave in different ways, not because they are different breeds just coz they do.lol! You will get the hang of it. You may not have time to put the fry into a new tank but fry usually float to the surface or hide in plants, so try floating plants on the top of the water for them to hide in. Get a small breeding trap and you can easily keep the fry in there for several weeks as they are tiny. It is amazing how many can get eaten very quicky by mum and the other fish. Also you need to think about if you really want all them fry and what you might do with them. As they wont be big enough to sell or give away before she next drops.
I am new to this but learning quickly. Good Luck and the first drops always exciting. x