Noms are not rolling, they have a drop dead due date, usually in late Sept/Mid Oct.
Not one nom will be given out until after that date has passed. You can submit April 1st, but you also can hurt yourself by doing so since you will probably take the SAT/ACT again and again. Most likely the superscore will increase. However, if you submit your packet with just the March SAT, that is all they are going to go off of for the nom.
You also hurt yourself by applying so early from the fact that you will not be adding whatever you do for the next 6 months.
MOC's right now what just place your application in a file and mark it 2017. They are really busy with 16 right now and will be more so for the next few weeks when the bulk of apptmts come out.
This is not a sprint, it is an emotional marathon.
JMPO, but sit back, study, take your ACT/SAT, and wait until summer before you apply.