I don't know if it actually makes a difference, but we keep a golf ball in every nesting box, just to provide a little reminder. Ours lay in their boxes 90% of the time, but every once in a while, we'll find one in the coop, and even less often, outside in the run.
I think it's normal for all birds to lay smaller eggs at first. I remember our first egg ever was no bigger than a ping pong ball. Our 2 EE's have been laying for about 2 months, and their eggs are very consistent in size, though definitely smaller than our birds that have been laying for a year.
Each bird seems to be different, though......some always lay smaller eggs than others......we have a columbian that only lays jumbo's.....our leghorns generally lay what I would equate to 'large', and the EE's that would be in the 'medium' range. Every once in a while, though, you'll get a rogue one....either gigantic, or tiny.......it's always fun to see what you get!