Last fall, I planted some garlic (read my post on that), hoping that come spring time I would be seeing some action in the pot. Sure enough by mid March I am seeing my first sprouts. I live in the southern part of the lower peninsula of Michigan, which is considered growing zone 5. So now if all goes well, my sprouts will continue to grow until they turn brown sometime in the summer, signaling that they are ready to harvest. This is my 3rd attempt at growing garlic but the first time I planted the bulbs in the fall, so hopefully I will have a much better result this year.
I can only speak of my zone, but typically early spring is when garlic begins to sprout, unless you live in a warmer climate.