How Long Does It Take A Guppy To Have Its Babies When It Is In A Breeding Net?

If you put a pregnant female in the net too soon she may withhold the fry from stress.  Guppies gestate for about 4 weeks so if it's been much longer it's probably not going to happen...
Just before a guppy drops her fry she tends to hang around away from the other fish in the tank and she won't eat. Watch for those signs and that's the time to net her.

My friend breeds guppies and she decided to provide a dense plastic groundcover plant and some largish riverstones in a pile in the main tank - the fry can hide in there to protect themselves and the strongest and fittest survive.

I have a pregnant guppy in the nylon net the rear of her is a big black hole how long does it take for them 2 have the babies