Probably, if the MO decides that your injury is not serious
enough.
Then again, whether or not they even want to see you earlier is
also their prerogative. Just contact them to ask whether your
appointment can be brought forward.
Whatever the case, remember that at the end of the day, the
greatest honour is to be able to go home to your momma in one
piece. There is no pride in getting yourself even more badly
injured by enlisting prematurely.