And when I had no answers, I asked Google instead. According to the Murray McMurray hatchery site, this is the answer:
"Most hens will start laying between 5-7 months of age. They will lay best at 1 to 2 years of age. All pullets (female chicken under 1 year of age) lay small eggs at first and after a while will lay larger eggs. Younger hens will lay 1 egg every 3-4 days. A hen 30 weeks old can lay 2 eggs every 3 days. Some have been known to lay an egg a day. All breeds have different laying abilities."So I have a little time before I really need to panic. They are getting pretty big though, and when I fed them this morning, one of them was actually up on the perch. They are almost fully feathered out now as well. By the end of May we should be grillin' up our first chickens.