I'm getting a couple of hissers and i'm going to keep them in a plastic faunarium tank.
Like this one:

but when the female gives birth the nymphs will escape out of the top right? So can you tell if they are going to give birth? then i'll put it in a shoe box or something.

if you have only a few then you can look at them closely and tell when the females are about to give birth because they become very plump.
however to save you from the trouble of moving them back and forth, i would just recommend a bug barrier or use vasoline as a barrier.

The female will start to look like she is splitting at the seams. You'll be able to see flesh between the upper and lower segments of her exoskeleton on her abdomen.