It is hard to do any two parks in one day..but it might help if you let us know a bit about what you enjoy? Do you want to do coster type rides, freefall rides, shopping..... Do you tend to attack the park at a run, or a slow walk? Will you be staying on site with front of the line passes? You get the idea.
I think you have a good plan by doing Universal first, and if you don't like coster type rides, free fall rides, shopping or wet rides you will spend less time in IOA... but it is still worth going to IMO.