Wait for about 3 months after point of lay to make sure the pullet eggs are large enough for a healthy growing developing chick. Your pullets are unlikley to sit on eggs either unless they are broody. If you just leave all eggs in the nest, chances are, they will just keep on collecting.
A hen will have to want to set before she willl sit on eggs, and if she wants to set, she will set on nothing even. Sometimes eggs in the nest will help encourage setting but not necessilarly.