I have three groups of chicks in my brooder right now. They will be 3 weeks, 2 weeks, and 1 week tomorrow or Saturday. If I just had the 3 week chicks, I would definitely have them on shavings by now but, with the one week old chicks, I haven't yet. How soon can I get rid of the paper towels? I think the shavings will be cleaner and certainly waste less paper!