This may be kind of academic at this point if you happen to be a Marine Option candidate. Like mattjr96, my son received his Marine Option scholarship during December last year -- which means he was selected in the November Marine Option board.
If you happen to be a Marine Option candidate and haven't applied yet, you're only chance this year would be the February board. This would mean your 1st semester grades would be considered.
What I don't know, and most really can't tell, is when the Navy boards meet.
The safe bet is to plan on having your 1st semester grades figure into the equation in my opinion.