My wife conceived soon after a cycle. On the ultrasound, it appears that the fetus has great traps and quads, and is hung like a bear.
Seriously, it is not possible for steriod use in a man to affect a child he may conceive. So there is no reason to delay going off birth control.
Your only concern is that use may lower sperm count which may make it difficult to conceive. That may just mean that you have a lot of sex for a long period of time. Oh the humanity!