I left the border on March 1, and got to Canada on July 11, so it was a total of 4 months and 11 days. That included about 16 days mid-trip picking up empty caches and laying out a new set of caches.
Water was a huge issue down south. That's probably the main reason the trail hadn't been thru-hiked before. With so few water sources, I needed caches. Because I had to drive the route caching anyway, I put out lots of water/food caches, so typically it was only a day or at 2 between resupply in the first 1,300 miles or so. Once I got to the Pueblos in Oregon there was more water so there were far less caches. After La Grande, Oregon, it was a standard thru-hike with no caches.
Timing the hike was a challenge. It hadn't been thru-hiked before so it was more difficult to judge how long the whole hike would take and to a lesser extent, what typical snow levels would be. The Steens were the first real concern, but the Blue Mountains come soon thereafter. Snow wasn't a big problem on this trip. On Steens Mountain, I had to do a short reroute because of high rivers from a rainstorm and snow-melt but other than that I was able to stay on the route. If I were going to do the hike again, I'd probably leave March 1 again. Much later it would get crazy hot down south, much earlier and snow would have been a much bigger problem.
Here is a direct link to my journal.