After my early losses I always O'd about two weeks later. It depends on how quickly your HCG levels drop back down mine always dropped quickly.

Doctors advise to wait a cycle before trying again but that's only so they can date your pregnancy should you get lucky again quickly. That said, I've been watching on BB for a while now and I've not seen that many ladies fall the next cycle, it's usually about 3 or 4 cycles on, some earlier, some later. So from what I've seen I think the thing about being more fertile after a m/c is a myth.

Remember that it's only about a 20% chance of conceiving with each cycle so the odds are it will take a few months. I had 3 pregnancies last year at at the age of 40/41 and the odds were not with me at all (in either conception or getting a sticky one) but I am due to give birth in a couple of weeks. I found TTCing straight away gave me a feeling of power which made me feel much better about the whole process.