history: My youngest son is going into kindergarten and I'm a little down. I'm sad. My youngest son starts kindergarten tomorrow! I am sure it is a bittersweet moment.  I can relate myself.  It takes some getting used to
current: I mean i'm happy for the up coming peace and quiet but it's still sad all my kids aren't babies anymore.
next: You will still have plenty of time before your son becomes an unruly teenager.  Cherish it.