My side rolling turners I lock down on day 13, the brinsea I lock down on 14 or 15. It doesn’t seem to make much difference in the brinsea, the side rollers definitely pip more often in the wrong place, the longer I wait to lock down.
If you look in the booklet, it has photos of the pheasant egg setup, which is 2 rows without the divider and they are just lined up in there. I use that for my larger eggs, and I’ll use the divider with smaller eggs. With the divider, one side is always slightly smaller, put them in starting on one side and put them in both channels as you go, don’t fill one side then the other. As you go, put fatter ones on one side and thinner ones on the other. I often have some really big ones and double yolkers and I’ll put one normal tray in with those.