You don't need to wait until 10 to avoid the traffic. if you're leaving Anaheim you can probably leave about 9:15 and hit minimal rush-hour traffic. What you do hit should disappear by the time you get to Tustin. The traffic that is still heavy at that point is going the other way. I would guess that a 9:15 departure would get you to the zoo by 10:45-11. Legoland would probably be 30 minutes less.