Moe's advice is very good and it reflects the consensus of a lot of answers to the question. I think if you are starting to wonder if it is time to move forward then it almost surely is indeed time to move forward. On the songs made easy, remember you can slow those down, too. If the lesson says the song is going to be 130 bpm, slow it down to half speed or three-quarter speed and gradually increase it.
Remind yourself that there are no deadlines here, and it is not a race or a competition. Enjoy the journey!
Dave...
It takes as long as it takes unless you quit - then it takes forever and you will never get there.
