Based on what I've read here in the beginner's guide and the stropping threads, it seems that most (including me) strop before every shave, and quite a few (also including me) strop post-shave as well. How may laps? Well, there's a lot of variation out there. I usually do 50 canvas/100 leather pre-shave, and 25 canvas/50 leather after the razor's had time to dry thoroughly post-shave. However, I've got 5 razors in rotation. If you've only got one razor, you may only need to strop once between shaves. How many laps? Up to you. Or if you're getting comfortable shaves without stropping, maybe you don't need to strop even that often. I can't do that--my face won't take it.
I have a pasted balsa strop (FeO on one side, CrO on the other) that I use only when stropping on canvas and leather doesn't give me a comfortable shave. I've got one razor that has seemed to require that more often than others; others in my rotation I haven't had to use that at all yet (I've had them all about the same length of time, several months at this point). So far I've only had to use the FeO side. Be aware that every time you use a pasted strop, you're removing metal.
Anyway, that 's what works for me. As always, YMMV. Good luck!