I bet Sheriff and VTechRoomie are right -- it will be NLT Friday.
It appears scholarship winners have 30 days to respond via email or fax accepting the scholarship offer after they receive the Army's official letter. Since the next/final Army ROTC board this year begins on 9 March, the Army probably wants to hear from the 2nd board winners before the 3rd/final board starts so they know how many open scholarship slots they can allocate. By my count, Saturday 7 February is 30 days from the start of the 9 March board, so the official scholarship offer letters need to be delivered to each recipient by Friday 6 February. Mail takes 3 to 5 days so letters need to go out in the mail NLT Friday or Saturday to make this timeline -- provided of course that all of my assumptions are correct . . .
. . . Best of luck to all