Pine shavings are fine to use after the first week OR under paper towels the first week. Chicks may eat the pine shavings and it's best to start them on paper towels.
I use paper towels over shavings for the first week and sprinkle some feed on the paper towels from day one to make it stupid-easy for them to find it and realize it's worth looking for in the corner feeder!
Good luck with your new babies!