vwtrey,
It's almost impossible to really come up with an "average" time it takes to solo. I've had students that were able to solo in 6 training sessions and then I've had students that took almost 2 flying seasons to solo. It's different for every student on how long it's going to take. It can also matter how much you can get to the field. If you can get to the field only once or twice every couple of weeks then it's going to take you a lot longer to solo. Whereas if you can go 2-4 times every week your training time will be less. Part of learning to fly is developing muscle memory and just like training for sports you have to train regularly for that training to be effective. I've had students that come out every couple of weeks or so and they have problems because the first flight or two each day is spent just "knocking the rust off" their skills.

If you really were to put my feet to the fire and make me come up with ball park figure I would say to give yourself 1-2 months as a ballpark

Hope this helps

Ken