Music theory is great, you can pick it up really really quickly... Sight reading on the other habd may take a little bit more... I took me about 2 weeks to learn to read notes at thier 1st positions and play them upto speed , Chords are something i still have serious trouble with.. but i mean all of it could be done in the space of one year... if your motivated enough (i'm self taught, and i can honestly say it's alot easier than you think... It always looks complicated and difficult when you dont understand something, then you understand it, and get insulted at how you thought it was difficult :))
Good luck...