I got pregnant after one cycle. We lost our first pregnancy, very early on, around 4 weeks, at the start of May. I am pretty sure I never ovulated but then a little shy of a month after the miscarriage I got my first period. 2 weeks later I ovulated, right on schedule, and we ended up conceiving this pregnancy. I am only about 7 1/2 weeks along, still very frightened but very excited. It helps that I had an early scan done last week and got to see my little monkey and it's heart beat.
I believe, at times, that a part of me is still grieving the baby that I lost in May. I talk to my babies, to both of them, it helps. I also believe that their spirits passed by one another in the loss/making and that they have a kinship. (I know that sounds weird, but?)
Anyhow, it can definitely happen quickly. I have read women who never have a period in between, I do think it is more common to get pregnant on the 2nd cycle though.
Good luck!