I have been lucky and never really experienced this. I find what works for me is that I actually hold the children very little. I interact with them and give them hugs but mostly I tell them to "go play with their friends" and I don't pick them up. They all settle in quickly and understand what things will be like at the daycare from day one. I think spending time outside is also key and gives them a chance to get a change of scenery/fresh air.