Well I got a BFP 2 cycles in, and they were both regular 28 days - it took 6 weeks for AF to return, followed by 2 cycles then the BFP. However, because I subsequently m/c'd, my cycles were then all over the place for the next 13 months until I got my second (and sticky) BFP.
My cycles ranged from 22 to 49 days, though usually fell between 27 and 33 days.
I am absolutely convinced that the delay in a second BFP for us was related to stress following the m/c though, and not due to my cycles.