I would arrive to the parking area no later than an hour before normal park opening. The walk from the parking area to Citywalk is a good distance even when riding the moving walkway things they have. If you happen to not run into much trouble parking and getting to Citywalk, this will leave you with a little time to look around Citywalk before walking over to IOA.
I am not sure how they handle rope drop at IOA anymore since I am not a morning person and just arrive an hour or two after it opens. I would assume they let non-hotel guests into the park about 15 minutes early but stop you before you can really get "into" the park. Somebody will come along and provide more details hopefully.
You need to do the HP area first. The crowds should not be THAT bad that early, but their will be a wait! With your limit time, I would skip Ollivanders because it normally has a long line and is just a small little show...its nothing really special and will save you some time.
I would do Harry Potter and the FJ first thing. I would also do the single rider line. It is not clearly marked, so just ask where to go. The way the ride works, you can not see the people sitting next to you anyways so there really is no point is waiting in what could be a 30-60 minute wait already. After the ride, you can go back into the castle and do the Castle Tour to see the stuff you missed by doing the single rider line. The Castle Tour is a great way to take pictures and stuff without feeling like you are holding up the normal line. If you really liked the ride, you can do it again in the single rider line. Odd are you will be able to ride it twice and do the tour in the same amount of time (or less) than if you waited in the normal line. If the line is 15 minutes or less, I would wait in it. Other than that, single rider it.
After that do Dragon Challenge. This ride normally never gets a long line so you should be fine here. After that enjoy some butterbeer and do some shopping.
Ideally you should be done with HP by around 11am giving you time to see some of the other stuff before you have to leave at three. I would leave HP from the JP side and ride the River Adventure (you will get wet, so if you don't want to get wet, skip it).
After that I would head to Spiderman. The crowd levels for this I am not sure about. The ride just got a makeover and reopens on March 8th. While I would like to think that this will not draw an even bigger crowd to an already popular ride, you never know. Since you will be getting to this area around noonish, the line could easily be up to 60+ minutes. They also offer a single rider line if you want to save some time. From there you have Dr. Doom and the hulk.
I left off the two "You will get soaked" rides between the River Adventure and Spiderman. If you feel like getting water on what I feel like are the best two water rides I have ever been on, go and enjoy them! If you don't want to get wet, you can skip them.
If you have time, you can head back over to the Dr. Suess area which you will walk through while heading to HP. Of course, if you don't care to ride the rides there and still have some left over time, I would go back to FJ and single rider it and then grab a Butterbeer (or two!) for the walk back to the car.
With March 13th being a spring break time, I am not sure how busy everything will be. If the parks are packed, just see the HP stuff and Spiderman...anything else is just a bonus if you have time. Enjoy your trip!
