My first commute was last May and the length is between 44 and 48 miles round trip, lately that depends on how much of the route is flooded. First few months last Summer I was cycling to to work 2 or 3 days a week and averaging one hour and 45 minutes each way. Couple of weeks last Summer I rode all 5 days and was just plain worn out by Friday.
Now five days a week is the routine and am averaging 1 hour 20 minutes each way and enjoying every minute.
Main differences for me are the weight loss, 60 lbs, and the increase in fitness. Also have figured out the timing of the traffic lights for the part of my commute on city streets.
I'm also very fortunate to work in a building that has bike lockers right outside the entrance and has a full locker room w/ showers in the basement. That helps minimize the time spent cleaning up after my ride in the morning.