By the time they have been eating their food for a week, they should be good at eating it. They will have learned that the chick starter in the feeders is food and be in the habit of eating it. Although they may sample some of the shavings at first, they shouldn't eat a lot of them, if they eat any at all. When they first come out of the shell, they just don't know WHAT they should be eating. They'll try whatever is there and some may over eat non-food items.
I've gone to skipping the shavings the first week and just using the paper towels, as I find that easier. When I want to switch them over to shavings, I put the shavings in and cover them with the paper towels for a day or so. Then I take the paper towels out. It seems to work fine for the chicks. Everybody has their favorite way to do things and lots of them work just fine. This is just what I do.
I don't think there's anything wrong with using newspapers underneath the paper towels. You just don't want to use the newspapers alone, because they are more slippery. Some chicks can develop leg problems. Paper towels over newspaper isn't much different than just using the paper towels alone, which a lot of people do. The chicks are still standing on the paper towels, which have more traction for them.
As they get larger and poop more, I think you are definitely going to want to switch over to shavings or you are going to have a smelly mess. They grow really fast and so does all that poop.
Shavings have a lot more surface area and it will all get mixed together as they walk around. You can also sprinkle some clean shavings on top, between cleanings, if you want. I do, since they are sleeping on the shavings.