Mine ended up taking about 7 or 7.5 qts after trans service.
Once you put it back together, add about 4 qts, start it up, run it through all shifter ranges and back to park and let it run for a couple of minutes.
Once it settles down, it should show nothing on the stick. Then add and keep checking until you begin to see fluid on the stick.
Run it through the ranges again, and fill just to the "ADD" mark. It should be starting to warm up pretty good by now.
Drive it for a couple of miles, allowing it to run through all gears icl OD, then recheck and fill to the correct warm full level. It may have expanded up to the normal range, in which case it can be left like that, or if it found some cavity that still was unfilled, it may have dropped a bit.
When I did mine, I bought 5 qts, as the older GM transaxles I used to do would only take 4.5 or so after a pan drop. I found that after 5, it still wasn't even showing on the stick, but was driving and shifting fine. I only had to drive 1/2 mile to the parts store to get some more ATF.