I suggest patience. Get your coop finished first. You really do have some time. Don't make it more complicated than it has to be.
There is no way of knowing when or even if one of your hens will go broody. It is purely dependent on when the hormones kick in. If you want to hatch eggs at a certain time and not rely on a hen going broody, an incubator is a good idea. If you rely on a hen, they may never go broody.
Collect all the eggs you want to hatch before you start. Life is a lot simpler if you start them at the same time. Staggered hatches, where they don't all hatch at the same time, can be extremely stressful to you and often to lead to bad things happening. I always advise against a staggered hatch, especially for the first time.
I don't like to hatch "pullet" eggs, especially the first few eggs they lay. It sometimes takes a while for the pullet to get the kinks worked out of her internal egg laying factory. Those first few eggs especially may not hatch. Give her some time to get things worked out.
But even more important to me, the pullet eggs are usually just not that large. They do not contain enough nutrients for the chick to develop to its potential. As a result, the chicks that hatch are smaller than they normally would be. They may or may not eventually grow up to be as big as normal. I've seen different reports on that. They will hatch. I set some pullet eggs one time and got a pretty good hatch rate. But I also lost several in the first 24 hours. Mine did not survive as well as the ones that hatched out of eggs from older chickens. I don't know what the magic age is. I hatched some from 9 month old pullets and they did great. The ones I hatched from 5 month old pullet's eggs hatched real well and the ones that lived past 24 hours had great energy and all that, but I lost 4 out of 8 those first 24 hours. I know other people have better success, but I'll have more patience next time.
