I don't expect you to have any problems getting hatching eggs for spring. I agree it is best to not try to hatch the tiny pullet eggs. If your Orpington had started laying at 18 to 20 weeks, those eggs would have probably been pretty small. Small enough that it would probably not have been a good idea to try to hatch them. But if they wait until 8 or 9 months of age to start laying those first eggs are probably going to be a lot larger and much more suitable for hatching.
Nobody can tell you when any specific pullet of any specific breed at any specific time of the year will start laying. One or more of your pullets could start laying any day now. One or more may wait until the longer days of spring. You just don't know.
I had pullets that I would normally expect to start laying around 5 to 6 months of age wait until they were 9 months old to start. Their first eggs came early in December when the days were getting really short. They broke all of the rules yet that is when 2 out of 3 pullets started. The third waited another 2 months to start laying.
