I've found that the children who tend to have the easiest time adjusting to preschool are the ones whose parents have talked to them over the summer about what to expect. They understand that they're going to be away from home for a good portion of the day, but that they'll have fun and that Mom or Dad will be there to pick them up later. They've also been reminded that the teachers are in charge and that they need to follow instructions, even if it means cleaning up when they'd rather go on playing.

Being prepared also means coming to school rested, not only on the first day, but also on the ones that follow. When a parent apologetically tells me, "She went to bed late last night," I know I can expect a day of whines, crankiness, or even off-the-wall hyperactivity. If you've been loose about bedtimes over the summer, this is the time to re-establish good habits. A preschooler needs 10-13 hours of sleep a night, according to the National Sleep Foundation, so depending on your family's morning schedule, you may need to set bedtime as early as 7:00 or 7:30.

Unless your preschool specifically okays it, it's best not to let your child take a doll or stuffed animal to school, even on the first day. In my experience, it's usually more distracting than comforting: While the teacher is trying to hold a discussion during circle time, the class is begging to have a look at the cool Lightning McQueen car or Rainbow Dash pony.

And jewelry? 4-year-olds put necklace pendants in their mouths, twist bracelets until they break, and slide rings on and off until they get lost behind the cubbies. It may seem cute to pile on the accessories for the first day of school (or beyond), but in the end, they're going to end up in the backpack.

The preschool environment probably won't look exactly the way it did when you first visited during enrollment time. Some sections of the classroom may even be closed off until the children have a chance to acclimate. For example, at my school, the shelves for our math games and science tools are turned toward the wall until we've spent some time explaining how to use the materials properly. So don't worry if the room looks a little bare; it won't stay that way for long!

I've seen plenty of students stroll into class with a smile, only to grow anxious when their parents became tearful or overly reassuring ("Everything will be fine! There's nothing to worry about! Nothing bad will happen! Be brave!"). Children pick up on their parents' emotions, and if you're sending out a fearful or sad vibe, they wonder if school is really such a great thing after all. A better approach: Stay positive and enthusiastic. Point out the awesome things in the classroom ("Is that a play kitchen in the corner?"). Look ahead: "I can't wait to hear all about your day when school is over!"

The moment you've dreaded will arrive: It's time to say good-bye. There may be tears, even leg-clinging and wails. Much as it may break your heart, the best approach is to give a hug, a kiss, and a promise that you'll be back when school is over... and then leave. The teacher will handle it from there. (Remember: We do this every year.) When I see parents hovering in a corner or coming back in again and again for one more hug, I notice that kids become more tearful, not less.

But the opposite approach — no good-bye at all — is just as harmful. Child psychotherapist Fran Walfish, Psy.D., told Parents that leaving without saying good-bye will frighten a child. Instead, she recommended that parents do a brief farewell ritual, then slip out once their child is busy making friends or playing.

By the time everyone in the class arrives, the backpacks are put away, the parents depart, and the children are settled in, a good chunk of the time will already be over, particularly if your school observes staggered part-day schedules for the first day or two. The full preschool routine — centers, gym, story time, lessons, etc. — won't start till later.

That first day may include a get-to-know-you song or game; I like to toss a soft ball to each child in turn and have them say their name and favorite food. The teacher will probably give a tour of the school, or explain routines such as going to the bathroom. Then the children might do a simple task, such as drawing a picture to bring home as a souvenir. By the time the end of the school year comes around, you'll be astonished at how your child's work has changed!

As any teacher will tell you, the first couple of weeks help set the tone for the rest of the school year. A class that doesn't understand or follow the rules in September will be downright uncontrollable by Christmas. So your child's preschool teacher will be spending most of those first days explaining and practicing such basics as sitting still, acting respectfully, transitioning between activities, and following safety rules. So don't worry if your child doesn't bring home a lot of worksheets or projects right away. At the beginning of the year, it's more important for a preschooler to know how to behave and socialize than how to count and sort.

I always tell parents that they're an essential part of their child's learning team. By that, I mean not just helping them master their alphabet, but also doing their part to help the teachers do their job more effectively. So keep the lines of communication going from the very first day. In addition to the important issues (food allergies, special needs, or family matters), it helps to know if a child has a preferred nickname, needs reminders to go to the bathroom, or doesn't take naps at home. At the same time, it's important for parents to stay in the loop about school. Check your email and your child's folder every day for class newsletters, announcements, and other information.

Here's to a happy first day and a successful year of preschool! Before you know it, you'll be getting ready for kindergarten and wondering how the time flew so quickly.