I have started using the cut down egg carton method (except for one hatch, for which all the eggs wouldn't fit if they were in cartons) and I like it.
You take your basic Styrofoam egg carton (less sticking of the eggs to the carton, as there might be with cardboard cartons) and just use the bottom egg holding part. Cut off the bottoms of the cups and cut down the sides of the carton so you basically have a collection of "rings" held together.
Set the cut down carton(s) in the tray. Put your eggs in the "rings," pointy end down. If you aren't setting enough eggs to fill all the holes, set them so there are spaces around the outside and maybe a space or two between some of the eggs. Close the 'bator.
With the Eco20, you are turning the ENTIRE incubator cabinet, setting it on the flat "octagon" spaces. Each time you turn it, you move it so it sets on the next, adjacent flat spot. Basically, you will start turning it back the other way when you have reached the "eight o'clock" spot and then back the OTHER way again when you reach the "four o'clock" position. Or vice versa.
On day 18, when you stop turning for days 19, 20 and 21 (and any that may be afterwards) just set the 'bator on the flat bottom again. Leave the eggs in the cartons for the hatch.