Definitely doable. I think a basic mario-like sidescroller can be done within 6 months to a year depending on how many hours a week you can put in. I started learning Python from Codecademy around December / January too, and Al's Pygame book around February / March, and this is what I've done so far using only Pygame.
Here is a website that helped a lot with planning which games to work on.
EDIT: Adding a couple of tidbits that I've learned so far as a beginner. Lists and dictionaries are your friends. When you're going through your Python course at Codecademy pay special attention to anything dealing with these data types. For me, personally, camera handling was a killer. So far this was the only thing I had to contact Al for help with. I spent hours upon hours just staring at the camera handling code, trying to understand it.