I have found this formula to be helpful and true…
Be aware of your own feelings. Try not to pass your anxieties on to your child. A positive and reassuring attitude from Mom and Dad goes a long way in easing the transition from home to child care.
Be firm. Say “Good Bye. Have a great day. I love you.” Try not to say “Is it okay if I leave?”
Be specific. Young children have a hazy sense of time. “I’ll see you right after lunch/nap” is better than “I’ll see you later.”
Be there. If there is going to be a change in the pick up routine, try to let your child know.