Some people keep them on towels...But its ok to put them on shavings- but keep an eye on tham to make sure they arent eating them. I usually wait until they are 3- 4 days old to make sure they really know the food is at the back of the brooder...and the shavings is not food.
What I do with mine when they come out of the incubator is have a towel placed over a half filled hot watter bottle for extra heat. The towel extends to where the food and water is on newspaper at the other end. I remove the hot water bottle after 1 day- leaving a towel still in the brooder. Once they have got the hang of going down to the other end of the brooder and are eating and drinking well- I change over to shavings. Usually on day three- but sometimes longer if I have had a longer drawn out hatch. Some people use puppy training pads- or paper towel as well as cloth towels. Its easier for them to find their feet and walk on a more flat solid surface for the first few days - but shavings can still be used from when they hatch as long as they dont eat them.
I have 3 call duck babaies 3-4 weeks old. 2 are in my tub which I clean 3x a day and just replace a washclothe for a dry spot for them-works great. The other was a sickly that is now great but since it hasnt been around the other 2 gets picked on badly when I try and place together:-( I use a towel in his little pen...They are supposed to get a new pen this weekend but its been pouring:-( They would all be going on shavings this weekend
we lost ducklings the very first year we raised them due to shavings.....they eat them when they are that young. We use paper towels with the rubber shelf liner for the first week or towels then put them on wire to keep things dry.
My runners ate shavings the first couple of times we tried them. Yes, ate - swallowed. We kept them on towels while they were in the brooder in the house.
Once they were three months old and outside, we bedded with shavings and they apparently were old enough to know better. They nose around in them, foraging, but no longer eat them. They even leave the pelleted sawdust alone.