I'm in the same boat as you. I'm taking my first week off in about 7 months. I can't wait until tomorrow, when I can lift again! I am especially excited because I have been doing a lot of research on these forums, and I have designed a routine accordingly. I have high expectations.
Anyway, prior to this routine I have been doing for 7 months, I had lifted on and off for a few years. I was seeing nice solid gains for about the same amount of time, 6-7 months, before results started to wane. A lot of people on these forums recommend taking a week off every 3-4 months, such as the previous posters. However, I have found that I can go longer before I need to take a break.
My new rule is that if I see no gains in 2-3 weeks, and I have been lifting steadily for a few months, then I will take a break. Otherwise, you probably just need to change your routine up.
