If I want to have another HT how long should you wait between procedures? The first one I had was to the hairline. I want to try and get some coverage on top and maybe a little more repair on the old plugs in a section of my hairline. Once the donor area is healed is it OK to proceed?

altair, at the very minimum, would be 6-7 months. And that should only be for a small procedure.
For a session you had, about 2000 grafts I would wait a minimum of 9 months to a year.

I had 2 small procedures of about 500 the first and 650 my second, and after 5 months so no more growth for either. Atleast any of notice.

I disagree. The key factor laxity. Once your laxity has returned from your initial procedure, you can move forward with another, subject to the grafts being placed in a different recipient area than the first procedure.

That is a good point also Hugh, but why run the risk of transplanting over existing grafts. I guess that would really turn to location. I would never do it, and wouldn't suggest doing it to for anyone.
It's just to risky to supply and demand.