If you do not have an interest in Hagrid's and just want to experience the parks. I'd suggest starting with US, not IoA (as typically US is the EE park, not IoA). They let people into the park early regardless of whether EE, or not. If you do not have EE, you'll can shop at the gift shop, or eat at the cafe there until officially opening time. You can walk around the Hollywood area (until a TM stops you) as well, or sit at a bench there. Then when they officially open, you'll be able to go forward (at least this way you've already scanned your ticket and in the park). Sometimes depending on crowds they will let you go and keep on walking into where the rides are a few minutes early.
I do not know if you plan to go anytime soon, but at the moment IoA at opening time is packed at the gate due to Hagrid's. So, if you want to be one of the first into the IoA park you'd have to be there at minimal an hour before hand to be one of the first at the gate and not all the way in the back of the line. So, to me, unless you plan on getting on Hagrid's there is no point at going to IoA first over US.
