I completed this over Labor Day weekend, so I had an extra built in recovery day.  Rented an amazing vintage cabin for the weekend less than a mile from the trailhead.  At 4am the closest parking spots were already taken, and numerous small groups were starting their journeys.  Clear sky and low temperatures made the first few miles decent.  All reviews that say the first 2 miles and last 2 miles are the hardest are very accurate.  Altitude struggles kicked in around mile 7.5 and my average time per mile slowed way down.  I went through a total of 7 liters of fluids on this entire hike, grateful for multiple water refill spots along the way.  However, all the struggles are very worth it for the sense of accomplishment when reaching the top.  Garmin clocked a total of 18.9 miles hiked.  I also rolled my ankle about 0.25 miles from the summit and descended over 8 miles on a sprain, kudos to the Altra boots I had on!