i think it depends of your previous qualifications.have you flown a turbojet , turboprop.Do you fly IFR?.there is a lot, but if you are a pilot with thousand hours, everything in the theory will be more exciting to learn.
Do you have a technic background, how do u master trigonometry, equation???do you anderstand physic...
I think there is no hurry to finish this JAR theory, 1 year should be allright.