If a wizard starts summoning on initiative 10(full round action) and I double move up to him around a corner initiative 9, so could not charge; Do I get an attack of opportunity as he finishes casting the next round? Or did I have to be next to him when he started casting?
See "Cast a Spell" in the Combat Section
When you begin a spell that takes 1 round or longer to cast, you must continue the invocations, gestures, and concentration from 1 round to just before your turn in the next round (at least). If you lose concentration after starting the spell and before it is complete, you lose the spell.
You only provoke attacks of opportunity when you begin casting a spell, even though you might continue casting for at least 1 full round. While casting a spell, you don't threaten any squares around you.
the start of the spell is the only part that provokes. Though you can be attacked normally and lose the spell before it goes off on your next turn.