Boarding school, we didn't have internet in the dorms at all, so I could only use it in the school library, about half a hour a day. I didn't use it very often (I had been using it daily for the year before I went there). Probably two months without?
After I graduated college, I was living with friends of friends. The first, um... hm, maybe a month, maybe six weeks, they didn't have internet, so I didn't have internet. I found a cafe while living with them, so I think I went a max of 3 weeks without it.
After I started camming, I moved, and there was a problem with the internet. It took 1 or 2 weeks for the company to sort the problem out. Was AT&T. I learned the following about their customer service: your first year with them, they are awesome, and after that, they are shit.