Leaving early isn't unprofessional in of itself. There are unprofessional ways to leave though, regardless of tenure, so don't do that. Make sure you're polite,

Leaving early isn't unprofessional in of itself. There are unprofessional ways to leave though, regardless of tenure, so don't do that. Make sure you're polite, don't focus too much on the negatives, hand things over properly, serve out your notice period if you have one contractually or legally.