Check out Backyardchickens.com, you'll find articles devoted to just this. If your birds are 8 weeks as of now, expect eggs around early September. They start laying around 18-20 weeks. Only add oyster shell if the eggs are actually getting thin, otherwise it can cause other problems. You'll want to feed them starter / grower feed until they start laying, then switch over to layer feed. Give your birds at minimum 2sq ft in the coop and the run size depends on how you plan to raise them, if they're getting out in the yard everyday to free range, then their run can be around 3-4sq ft per bird, if not go bigger on the run size. I have 4 birds, the coop is 3x4', and the run is 4x8'. I let them in the yard to eat weeds, bugs, and stuff about 1-2 times / week for a few hours, while I'm drinking my morning coffee on the patio. Supervision is important, for hawks, cats, and dogs..

They're pretty easy to raise and care for honestly. If you plan on raising them for meat when they stop making eggs (~3 yrs), try not to get too attached. lol

Since you're building your coop , check out the "deep litter method", and there's pics out there of feeders and waterers using 5 gal buckets, that are pretty slick.

Hope this helps, good luck!