I will tell you what I did.
As I was just beginning, I lengthened my rides carefully until I reached a distance that is effective for a short workout I planned to do. Then I began to do that workout once or twice a week and continued carefully increasing the distance on the other days until I reached a good training distance for my longer workouts. At that point I began to focus on doing the workouts properly and getting faster, but one ride per week I continued to allow to get longer (and very slightly faster).
I started at the beginning of June, barely able to complete a moderate effort 7 mile ride. Yesterday I did a 75+ mile group ride. My 1hr time trial has gone from 14.2 mi/hr to 20.1mi/hr.
One more thing. When increasing the distance, 10% per week as an upper limit gets thrown out a bit, but it's just a rule of thumb. Listen to your body carefully, it is the boss. Having said that, most of my long ride increases have been 5% to 10% longer in time, so because I was also riding faster, the distance increase was often greater than 10%.
Good luck, feel free to add more specifics to your questions, it'll get you much better answers in these parts.