When/How to add Prime?

I got really into wanting a tropical fish for my 5gl tank and despite my ignorance thinking "It's just a fish, how hard can it be" I have done plenty research and come to understand most of the ins and outs of basic fishkeeping. One thing in the future when I set up my tank again and begin fishless cycling, is how often to add prime? Seems ridiculous I know. Will the ammonia re-bind after 48 hours? Or once added, can I just leave it to the next water change? I live in the UK and it's common here to have heavily chlorinated water. I don't want the chlorine to kill the BB and when I eventually get a fish don't want it to die. Re-dose every 40 hours? Or once added, leave it as if it's fine?