Hatching CL pullet eggs?

[its hilly]

My little cream legbar hen has laid an egg every day up till now. They're around 50g so not a bad size cos she's not a lot bigger than my banties herself.
What I'm wondering is how long should she lay before I should hatch any eggs? Or any of my hens actually, as this will be the first lay for any of them? At the mo they're all in a mixed group so I'm planning to stick the CL girls and two CL boys in a seperate run for 5/6 weeks to make sure that anything I hatch is pure, or would I be better off leaving it till shes been laying for longer? and if so how long?

[RichmondHens]

Depends how long she has been in lay, but if she is settled in a regular laying pattern then it will be fine to start breeding from her. I would personally plan for a March hatch as the weather (hopefully) will be a bit milder then and the grass will be starting to grow, all of which will benefit the chicks. The lengthening of days will also increase fertility. The cock only needs to be with the hen for 10 days - 2 weeks to be sure he is the one fertilising the eggs. Good luck!

[its hilly]

Thanks Richmond.
Think I'll leave it a bit longer, then I may have some others laying too. And theres bound to be some tempting eggs at Carlisle in Feb

[Bramble-Poultry]

If the girls are in regular lay then you can hatch, leave her eggs for a week or so two after you seperate them to ensure purity