Yep, I believe, it's possible to pre-pone it.....as long as one walks in early in the day like 8/9...(like Wednesday/Thursday)....when there is no crowd and you have a valid FP notice...Check out this user, HaraKad...he did that...
THe officers, I heard, usually accomodate...as long as...there is nobody else waiting...if there is crowd, they may ask you to come back again!
