That's hard to predict. It's different for everyone.

Myself, I only had to stop and rest once on my way home from the LBS with my shiny new bike. The total trip was 0.67 miles. Yes, I had to stop and rest after a third of a mile.

At the time I was working at locations, 2 and 3½ miles away. It was about two months before I could get all the way to work without stopping to rest. In those early days, I hoped for red lights, and cursed green ones.

Mine is probably one of the more extreme cases…

That said, in five months I did my first half-century (50 miles), my first metric (100km, 62 miles) came at seven months. But at the time I was essentially stringing together a bunch of 10-mile rides.

These days, I changed my workplace location to one a little further away, 4½ miles, since commuting is about my only exercise in the winter. This way I get in a minimum of about 50 miles a week. Weekends 40-50 milers are my favorite, and I have no trouble at all with double that.

The advice I never had a chance to follow, because it wasn't for a couple of months that I discovered BF, is take a test ride on the weekend or another day off. That'll give you a chance to evaluate both your route and your motor.