I'll be the oddball and say the only way I paint ceilings is with a sprayer. I couldn't imagine how my neck would feel after trying to cut in a ceiling and roll it. The sprayer will take less time, and you can't beat how even it will go up.
After spraying, I'd vent the room and start any lower cutting until the overspray onto the walls dried completely.
For cuttting I use a purty 3" slant cut brush. I also only put paint on the wall side of the brush (hold the brush up as if you were cutting. Swipe the side facing the ceiling) Cutting is only a matter of putting the bristles of the brush into the 90 of the wall/ceiling and pulling it smoothly across. The 90 will determine your line, and your hand will determine how well you stay on that line. I'll cut like a 3 ft. section and then I swipe the brush the same way as I did when I was going to cut the line (except I load it more) and I'll run the brush vertically in a horizontal stroke to cut in 3" from the ceiling. This also lets me smooth the paint out as a "finish" stroke, where the first step I was just making the line.
Roll 2 coats, and clean up. I'd say 7-9 hours.
I just switched paints from Behr ultra premium blah blah flat enamel (after 2 years) to sherwin williams duration home. The behr seemed to go on fine for me (maybe I became used to it) and looked good, but wiping anything off the paint for the homeowner instantly leads to a yellow tint to form. The sherwin is more expensive, but is the best paint I've used. It goes on great, covers like no other (that I know of), and is like a dry erase board when it dries. You can actually write on it and wipe it off, which was the only thing I was missing with the behr. If you want a comparable to the behr, a little more costly but won't yellow when rubbing, you can go with the sherwin williams cashmere. Sorry for the long post.