If your move falls under the prorated pricing process (meaning, if it is not a long-distance move or billed independently), your estimate has been calculated based on the amount of time you reserved. If your service is completed before the minimum is reached, then you will pay the minimum amount. The minimum is two hours for movers only, and three hours for movers and a truck.
This to-the-minute billing gives you the most flexibility, rather than charging you in large chunks of time whose full duration you may not need. Finally, if you booked a local move, travel time between locations is considered billable during your move, so please be sure to consider that when scheduling.
Should your service extend beyond the minimum, you will pay for the amount of time your service requires.