Granted, I don't really know much about this (my kids usually tell me to 'go away' as soon as they get to camp/soccer/gymnastics/school because they're fiercely independent), but some children have a harder time transitioning to full day kindergarten. There might be clinging and tears for a day or two, or it might continue for weeks, depending on the child.
There are tons of web resources and books out there, but a good (and important) strategy is probably to talk to your teacher to find out how she prefers to approach the situation. It's not like she hasn't gone through it before with hundreds of other five year olds. She'll know how to smooth the transition with minimal disruption to other students.
Some schools ease in, with half-days the first week... but not at Daniel Bagley. You will, however, be able to escort your child directly to the classroom at drop-off, and come right to the classroom door at pick-up, during that first week.
Getting the school year routine down takes a bit of practice, and be prepared to adjust. The ultimate goal is reducing stress for parents, kids, and teachers. And, a little bit of distraction (fun times at the playground, new buddies) can be very helpful.
A great way to make it easier: come to playdates and the Welcome Night social, so your child can familiarize himself with the school, and meet the other kids. Then it will not be so scary and unknown.
That's all I've got about this - just be prepared! Your always happy-go-lucky kid might be in total panic mode once he sees the 400 other kids, most of whom will seem like giants. Or, maybe he'll be excited and oblivious, all at the same time.