A straightforward double-door swap on a house built to late-'90s specs is usually a single visit - old door out, new door and hardware in, opener reconnected and balanced. Houses with header damage, an out-of-square jamb, or an opener that needs replacing alongside the door take longer, and we'll tell you that during the estimate, not after we've started.
Severn sits about 10 miles from Columbia, which is a normal run for us and doesn't add anything to the job itself - we're not quoting a faster or slower job because of the drive. What does change the schedule is parts. If you want a specific finish or a custom width outside the standard sizes this area's houses were built with, that's an order-in item, and we'll give you a real lead time once we know what you're after.