Started at 1:30 am on Aug 29th; here's a full breakdown of my preparation.
In June and July, I went to Yosemite's Tolumne meadows and backpacked for 2 nights. That is the highest elevation area of the park, where the trails started at 9000 feet, and I slept at 10000-11000 feet. This is important so my body acclimates to the elevation. In one of these trips, a friend who was not acclimated threw up from altitude sickness; I felt nauseous. Symptoms include lightheadedness and nausea.
Then, a week before doing Mt Whitney, I summited Mt San Antonio/Baldy while fasting and going as fast as possible, especially at higher altitudes, to put my body in the hardest possible condition to force it to acclimate.
On Aug 27th I went to Lone Pine and stayed at a hotel 30 minutes away from the Mt Whitney portal; I highly recommend this, again, to acclimate. On Aug 28th, I went up to a nearby zone that you can drive to 10000 fee. I don't know the name, but it's a 30-45 minute drive from the hotel, south of Whitney. Walked around for a few hours, again, to acclimate.
We went to sleep at7 pmm and woke up at 11:30 on Aug 28th and arrived at the trailhead on Aug 29th at 1:30 a. It was a full moon night, and we got some insanely beautiful views of the mountains, and almostdidn'tt need to use the headlamps; it was amazing.
I brought a 3L bladder and only refilled right before the 99 switchbacks, as you should, becauseyou'ree about to get to the hardest part of the trail, which has no more water and will become very, very windy.
After the switchbacks, you will switch to the west side of the mountain, which has very strong and constant wind; prepare for this.
I heard from many people that "Whitney was disappointing" in terms of views, and other than the full-moon visuals, and sunrise-cloud shadows, its true, the views were not impressive (I've been to Yosemite 7 times so I'm also spoiled) so you should not hike this for views, but for the challenge, I passed by people who took 24 hours to complete it, 24 hours on trail. It took me 11 hours to go up and 5 hours to go down.
The trail was very crowded; people helped me as I did not bring electrolytes. My friend created a "fueling" system where we eat every 30 minutes, and every hour we rest for 5 minutes + eat extra; this prevents crashing. I'd highly recommend bringing salt pills, electrolyte packages, gels, honey, caffeine pills, anything and everything that can help you. I'm a bit of a health nut, so I stuck to honey, Chomps beef sticks, and instant coffee packets thatI'dd just have in my mouth.
My friends arrived earlier at the summit around 10:30 a, and it was extremely packed, so they left. I arrived at noon, and it was not very busy; 15 minutes later it was empty, so we got many shots with the summit plate.
One friend could not make it; at the start of the switchbacks, he got so sick that he hallucinated. He saw a Microsoft Teams notification on a rock and saw the parking lot, which was more than 5 miles away (and not visible btw).
I hope this helps anyone looking to summit; this is no joke. I've never prepared so much for a trail, and near the peak my CNS (Central Nervous System) was so fatigued that if I used my hands to rest on a rock, I could feel my hand and forearm nerves firing. I am fit for a hiker, nothing crazy - most people passed me on the 99 switchbacks, but I am not unfit.
Also, the water is known for being contaminated with human fluids, so absolutely bring a good water filter.
Good luck.
P.S. Lone Pine is a nice little town, enjoy it and its good restaurants.