I wait until it goes from a stream to a drip.
I also crank the dry engine with the old filter on first. It seems to clear the pump oil and the filter itself. I used to crank it after the filter was off, and it would spit out some oil, but with the filter on there is no mess from the pump oil and the filter is empty.
fwiw, it you look at the actual capacity specs for a rebuilt engine, it hold more than a quart inside. imo, a good reason not to over-extend ocis.
I have a good solution for totally cleaning the engine out. Use a jug of basic oil to flush it out (engine running for a few seconds) and save that oil for reuse. It can probally go 4-5 times and still come out clean then us eit in a mower or whatever.