I keep a calendar on top of mine. On the set date, I list how many of what kind of egg is set. Then I mark the hatch date on the calendar right away. 2 weeks ago, I still screwed up and had a couple chicks hatch in the turners. Now I put a piece of styrofoam egg carton with the set date marked on it tucked into each tray. So far, so good.
I was marking the eggs themselves (2-3 each set, and each set has it's own tray or trays). It was working, but then I got lazy and thought I could just remember on my own. Yeah, okay. So far I haven't had anyone hatch in the turner because I candle every week. Now, this will be a setting I get confused on because I just set on Saturday and I have to set again tomorrow night. I am getting way more eggs than I had planned.