After they finish. After you see the condition of your belongings. I got a TV back with a hole in it. No tip there.
What is everyone's thought about tipping movers? I'm moving next week, and I know I am going to tip the movers, but should I do it up front before they start, or after they are finished?
Definitely after they have finished. You only tip after the service you paid for has finished.
Definitely do it afterwards. They will do a better job that way because they will know getting tip depends on how well they work.