At our school we have an evening right before school starts where the children come to see the room and meet their teachers. We call it an Open House as they may come anytime within a certain time period.
Some years ago, when I was on maternity leave, the teacher for the 3-year-old class came up with such a cute idea. It works really well, and I still continue it today.
She created a scavenger hunt type of game for them to do with their families. When the children arrive we introduce our selves and welcome them to the class. We then have a paper with some objects on it that we give them. They are not as much objects as they are places in the classroom.
The family takes the paper and travels around the room looking for the specific spots listed on the paper. At each place I have some small stickers. When they find the spot, they take off a sticker and place it on the paper. After they are finished they bring it back to me and I give them a name tag to wear on their first day of school and a small snack to eat later.
This helps ease the children into the room, plus it makes them walk around and see the many different places there are to enjoy themselves.