I was going to say that.

girljen, not to sound insulting, but what is your "starting" fitness level? I remember my first bike commute...9 miles, and I thought I was going to die. I didn't think it would be a big deal, since I was a regular runner, to the tune of 3 mile runs several days per week. Hoo boy was I wrong.

If you're starting from your couch, per se...it may be a while.

For right now, don't force it too much. Over that short of a distance, the difference in time between giving the ride all you have and spinning a little easier won't be hugely significant. In time your fitness level and your riding strength will catch up. Then you'll be posting back here about wanting a different and faster bike to keep up with your abilities.

Congratulations on starting. I promise you, it gets better. A lot better. So much better that you'll feel a bit irritated at the days where you have to drive for whatever reason.