Staggering your chicks is a good idea, at least I think so and practice that very thing. I also alternate between birds that I fancy, ie, Barred Rocks, Speckled Sussex, RiR, etc and a flock of production birds. When you have egg customers, such as we have, we need to have a certain supply year around. I also carry a few extra young hens through the winter, because laying does slack a bit during the "dark quarter" of the year.
I like to start a spring batch of chicks in late March and then do a fall batch in September. Check with the hatcheries you like. Many keep mailing chicks right through September, no problem. Even up north, here where we live, they are all feathered out good to go into the unheated barn by November and tolerate the winter better than the older girls. They're young and have lots of heat energy.