Chicken manure is considered hot, which means it's high in nitrogen, and can burn plants. So the common advice is to compost it before putting it on a garden. In practice, with the chickens dropping a little here and a little there, I doubt you're going to have a problem (it's not like there are little burned spots on the lawn where they pooped). But it is something to be aware of.
I wouldn't want the chickens in my garden anytime soon after I planted, though -- whether I planted seeds or starts. They'll scratch up the seeds, pull up the starts, and chew on everything else.
Here's what I do, though. I have the chicken run next to the garden. Both are fenced (I need the fence around the garden for the deer anyway), and the fence in between the run and the garden is more-or-less temporary.
Then, as soon as we finish harvesting in the fall, I take down that fence (just the part separating the run and the garden), and the chickens get to glean everything left behind. It also gives them access to the bug- and worm-rich soil. They have a blast, it cuts down on my feed for awhile, and it helps with the garden. I leave them there until early spring, and then put the fence back up a month or so before planting and till the garden up.
I am super excited to welcome you to BYC!!! I can ensure you everyone here is great and super helpful, yes sometimes we can butt heads but if that happens it ends fairly quickly and with an apology. I gotta ask if you are interested in any egg colors specifically because if so easter eggers are great, also black and blue copper marans are a favorite of mine as well. And good foragers are Brahmas, And If you want to be self-sustainable I think it is key to have a more broody likely hen like a Buff Orpington or a silkie. If you can hatch chicks with a hen rather than an incubator it is one less thing you have to worry about in a sense because I still worry when my hens are sitting but you don't have to rely on power or anything else. If you have any questions just let us know. 
