I think mine was about 2 weeks. I actually emailed AMHA and checked on them. They had gotten the DNA results back and working on processing the updated certificate. It took a few days after that to receive. I'd say 3 weeks max to be safe (counting the weekends in there). I just got mine back about a week or so ago - so that's recent.
I agree with Songcatcher. Length of time can vary a lot as UC Davis can be pretty slow. AMHA is having a pretty fast turnaround on paperwork right now, so I think as soon as they get the results back from the lab, the paperwork will be processed promptly. I'm waiting on 3 to come back right now.
yea, I didn't think 2-3 weeks was bad really because I had thought about all the foals being registered this time of year too - figured they were all busy. My DNA went hand-in-hand with the transfer work of this stallion too so I didn't have any compalints really about the time it took to come back. I'm getting ready to send another batch of paperwork off and so far have been pleased with the turnaround time from AMHA (including them waiting on the DNA results). I like the fact that AMHA will call or email if I've missed something either in paperwork or fees - and they asked questions to clarify what it is that I was trying to do (LOL). They pay close attention to detail and I've been pleased.
I think my DNA tests took about 5 weeks. I think it was some thing about the paperwork. I signed and sent it with the sample and should have sent the paperwork to AMHA. Oh well, my bad.