3 to 3.5 months is no problem if you want to do it. I hiked in 105 days in 2003. My friend Will (now Pony Express) did it the same year in 100 days. Birdie did it in 105 days also. I had the best time of my life hiking the PCT and wouldn’t trade it for anything.
See http://www.pierce.ctc.edu/faculty/cwillett
where you’ll find an account of the trek and some bad pictures.
See also http://members.tripod.com/gohike/
for Dave Brock’s excellent write up of his 2002 hike, which was also on the order of 3.5 months.
The biggest problem you’ll find with doing a hike this way is from other hikers. They assume that their way is right, and can’t imagine anyone else’s possibly being correct or desireable. I tended to be hiking as the sun was coming up, as it was cooler then and the early morning light is spectacular. I also liked to hike in the early evening, up until sunset. Again, it is cooler and the light is amazing. So, this meant that I put in long days and big miles, even though I don’t have a fast pace and take a fair number of breaks. My days were all very intense and I can still remember special features of each one. I was focused on being out hiking, not sitting around camp or in towns, so I took few zero days. Rather than, say, 30 zero days (which seems common), I took something like 7. So, take my 105 day hike, add on 23 zero days, and come up wiith a hike that would have lasted a little over 4 months, which is rather common.
Just get out and hike. If you finish, fine. Else, it doesn’t matter much. Enjoy the time you have and don’t let others dictate your style of hiking. If you want to slow it down and hike 12 mile days, do so. If you want to cruise along at 30, do so. Just don’t constrain yourself one way or the other. It is your hike, and it is up to you to enjoy it.
Suge