Admissions are based on a rolling basis armyman736. Its not generally a one shot deal that they look at it, you're done. You should complete it as soon as possible and update as you can. Couple reasons for that -
1) it shows you're motivated and shows you are serious - this will also be beneficial for you when you go in for your congressional interviews as it will translate to you being serious and not wasting their time
2) you get it off your back...big deal when its senior year and all your friends are obsessing over college apps and you can kick back and relax
3) if something comes up, especially when it comes to DoDMERB or items sometimes needing clarification, you won't be rushing to meet deadlines, keeps stress level down
4) I can't verify this, but I've heard from admissions counselors/cadets while I was at SLS last year, but the bar for the WCS (whole candidate score) keeps getting raised as more and more candidates complete their files, increasing the competitiveness, to be granted an appointed as the year progresses; for sure, it doesn't go down. If you're borderline, its best to get your application in as soon as possible so that it can get in front of as many boards as possible and make an earlier cut