Most people switch at 2-3 days, I started them out on the shavings and never used paper towles.
This year I'll be using pine pellets instead of shavings. The amount of dust from the shavings was CRAZY! The pellets are supposed to be much less dusty and I think they'll work better for odor control too. I started using them in the cat boxes a few months ago and they have made a huge difference in odor control there.
Thanks all for the great advice. My chicks have been in a plastic tub brooder for five days. I'm building a new brooder today and transfering them over tomorrow. I only have 21 chicks right now but have 56 eggs in the hatcher that are due to hatch Friday or Saturday. I already have a large bag of pine shavings for my rabbits so I'll try that.