I agree with mickyc. From day one, I don't pick up a day care child unless they are hurt. Yes, it's hard, especially the first week or so where they are just adjusting to a day care environment.

I will go down to their level and am normally on the floor with them and I don't mind at all if someone plonks themselves on my lap but I find it way easier to start this way, and lighten up, then to break the habit of a child who wants picking up all the time from the get go.