did mine at 40k. no issues at all . if you do like i did and forget to put the magnet back in the pan you get twice the practice!! the bolts that hold the pan on and the rubber gasket can be a little tricky, remember to snug all the bolts a bit before tightening to keep from pinching the gasket.
also i broke loose the trans line at the rubber to hard line connection and put it in a jug. started the car and went thru all the gears which took 5 sec? drain most of the fluid out of the t/c. refilled and basically had a full flush
while doing this i suggest you go ahead and replace the tranny plug elec. connector that has a habit of going bad. no need for tranny oil to run down your arms twice!!!