As TP4 said, except for Despicable Me, the lines aren't bad anywhere. Universal has added a lot of capacity in the past few years so they don't have the long lines like many of the better WDW attractions. But yes, start at DM and then do Diagon & Gringotts, Transformers, Mummy, MIB, Simpsons. Take the HE over to IOA and you can do FJ, Hogsmeade and the headline attractions at IOA. Then you can get on HE and return to Diagon (That way you get to experience both HE scenarios). It's essential you spend the evening at Diagon since it really shines in the dark. But you'll still miss a lot since IOA and the Studios are really a two to three day experience at the least. Though you should be able to do a decent number of the headliners. And Diagon has so much to explore and investigate that you can easily spend a day just there.