Leave for work with enough time so that if you flat you will still be at work on time.
Wind direction will dramatically affect my commute times, so watch out for that.
If you are doing a partial commute, it may help. Drive in with the bike and cycle home, and do the opposite the following day, do it both ways on Friday. (No time worries if you are slower Friday night, and rest days coming up!) If you drive partway and cycle the rest, returning to your car each night, then you can be really creative: Strong east winds predicted for the evening? Park to the west side of work! Park so you have a more pleasant route! Feeling tired? Park closer. Building your endurance? Progressively park further away.
Don't let your commute get stale or burdensome.