After a first FUE, how long after can I have another FUE hair transplant?

You should wait at least 10 months before your next procedure. You should speak with your surgeon and have him/her examine your donor area.

For the second operation you should wait 10-12 months. After than you can speak with your doctor about your donor area and the healing time.

It all depends where the grafts from the second transplant are going.  For vertex cases, we generally want to wait a minimum of 12 months before transplanting into the vertex a second time.  For frontal forelock and hairline cases, 10 months is fine. If the grafts are going to a place that has not received grafts in the past, then anytime is ok.