I've been training for about 2 months now. We don't have grades or anything like that, which is one of the reasons I like Muay Thai.
Do you learn certain techniques at different stages? If so, it sure is more organized than how we learn. I'm not sure if the instructor has a lesson plan. It just seems like we just learn stuff as we go. My friend has been training for over 4 years though, so he teaches me stuff we haven't learned =P