With modern day paints, it is preferred to let the cut ins dry completely before rolling. The days of trying to roll while the cut ins are still wet are gone. The paints just dry too fast. You don't need to wait a day though. Usually an hour is enough, sometimes a bit longer depending on the drying conditions. What I usually do with high rooms is cut in the ceiling line and then roll down from that a bit right away so that I don't have to risk getting close to the ceiling when rolling from the ground.

Definitely cut everything in and let fully dry. Yes, it may be 2-4 hours. Every homes' different!!

Low-VOC paints especially dry very fast. Too fast to reasonably keep a wet edge. WON'T happen anymore.
It's just the "new normal"!

When rolling over your cut-ins, ease-off with the roller-pressure there, if you're paralleling the ceiling line.
You want to apply only roller-stipple on the cut-in...NOT another full coat!
It's just a finesse touch which helps avoid the "hatband" look!

Faron

When you cut in, feather the edge out 8-10 inches (one handspan), ending up with a solid cover near the corner and a really wispy edge toward the center of the wall.

Like paintguy, I roll the top part down a bit as I cut in, using a small roller and tray.