Just to ease the pressure, everyone in my husband's NSI class (a May class) was turning acceptance letters in right up until before they reported in, however, as someone pointed out, the schools will try to accomodate STA-21 students w/ earlier acceptance letters (they know the Navy pays their bills on time!). If a school goes "huh, you're in wha?", call what would be the receiving NROTC unit & see if they can give you advice.
Another piece of advice, as soon as your taxes are done, apply for FAFSA. You'll only want to accept grants, not loans. Some of you may max the grant award (I think that's $4,500 per year, we have people here who get the max) & some of you may get nothing but it's free money to go to school. The Navy will be paying for your books (by reimbursement so save some book money for every semester) & your tuition (up front) but FAFSA money can help pay for your daycare, travel expenses to & fr the school & so on. Also, save all your receipts. The message regarding reimbursement for application expenses is very ambiguous & some of you may read that thinking "the Navy is going to reimburse me for applying to 3 schools" but nope, the receiving NROTC unit will reimburse you your application fees for the school you actually get ordered to however you hardly want to be the person checking in & asking for money in the next breath so save your receipts, make copies of your application fee payments (copy the check/money order/etc) & anything else associated w/ getting into college (fees for transcript records, etc) & plan on just taking it off on taxes, get a tax expert (CPA, accountant, etc) to do your taxes for the next 3 years.