I was 20, booked test after first lesson, had 9 more including the one before the test and passed first time.
The DSA does NOT recommend what you say - they give that as the average NOT a recommendation.
There is no way for anyone on here to judge whether you will be ready when you are asking about. You may need only half that amount or less or go on for a couple of years and never pass and anywhere in between.
I know you are looking for some reassurance but if anyone gives you a "yes you will be OK", then come on, they do not know you, do not know your abilities and simply have no idea.