I use a second tray on top of the tray being harvested. Not all the worms move up. so I still have a little sorting to do.

I add new trays on the top when I run out of room, so the worms migrate upwards when they're ready (or when they think the new tray is interesting enough). After the bottom-most tray is finished, I put it on top and take the top off to let it all dry out a bit and encourage the worms to migrate down. They do that pretty quickly -- maybe a couple of days. I encourage the process by stirring that top bin once a day or so. After that I have very little separation to do.

Cindy

I use lateral migration. My tote bin is divided in half with a wire baking rack mounted vertically in the middle of the bin and only one half is used at a time.

Here is a link that might be useful: BorealWormer

I do something similar to Cindy. I put the finished tray on top of a tray with fresh bedding, leave the lid off, and let the worms burrow to escape the light. I scrape off layers or alternately only put a couple of inches of the finished mixture into the top tray and they all migrate down to the fresh tray. It only takes a couple of hours at most.

I have since built a harvester that separates the finished VC from the worms and unfinished VC. It's handy because it's fast and because I can just deposit the worms and unfinished food/bedding back into the bins. Easy breezy.