I sent my P4 back for a hardware failure problem a month or so ago. Took 5 days to get there, 2 days to repair and ship, 5 days to get back to me. So I guess you could say it is almost 2 weeks from start to finish.
I can't say enough about how good the service is from DJI. Had a P3P before the P4 and got the same kind of a service turn around on a repair on that as well. And both were under warranty, so they paid UPS charges both ways.
I see a lot of comments about how long it takes for a DJI repair, but so far, with two different repairs I have not found that to be the case! It is the travel time to CA from MI that slows things down. I would guess that if you wanted to pay, both ways over night shipping, you would get it back within one week!
And my P4 is just fantastic to fly. Everything works perfectly, and the hover is motionless on the camera screen. And I also had the yoyo effect, and it is now completely gone. The bird stops and sets perfectly still, no more up and down drift.
I think that DJI get a lot of bad press on their service and repair. I just wanted to let all know that it is always not the case, I have been extremely pleased with their response and turn around time on repairs.