How many months or weeks after hair transplant is it safe to perform 0.5 - 1 mm dermaroller microneedling on the recipient area?

It is best to contact your doctor about post operative care and instructions since each doctor has a different regimen.

Although micro needling can stimulate hairs to move into an anagen state, this effect is really a temporary effect.  It is useful when combined with PRP to bring more platelets and growth factors to the surface, but outside of the in office uses or micro-needling, I don't recommend patients to do any of this at home.  At best you will get inflammation or infection. 

I would not recommend that you use a dermaroller with microneedling as you might introduce an folliculitis to your grafts