4.5 hours to solo on microlights though with some previous on gliders though a few years before. Didn't complete the PPL that time though when I got back in the saddle 12 years later it only took 6.5 hours to solo.
Bear in mind that your time to solo is down to three things: Your competency, the weather (i.e. your currency, how often you can fly) and your instructor's comfort level with sending students solo. Some are fine with it if they think you are ready, others will keep you dual for as long as possible to be absolutely certain that you are ready. Most fall in between.
It may be that you really aren't ready but if you are convinced that you are being held back unecessarily there is nothing wrong with asking for a hop with a different instructor to get second opinion. I did exactly this when gliding and soloed after a 5 minute check out with a more senoir instructor than my regular one.
Flying is an expensive thing to learn. Its your money, and there's nothing wrong with questioning (politely!) those who are providing your training.