New batch of layers, Day Old

We have just taken delivery of our first batch o day old chicks, these are Black Rocks which we hope will be in lay before november 09 . That means they will lay through the winter , another 4 weeks later and we risk not getting any eggs until after the nights draw out after December 21st.We put 25 chicks under each broody, they seem to be able to cope fine and produce healthy laying hens.