I think early morning or late evening are best for timing, just depending on how your sleep and ghrelin are.
With early morning you can have your last breakfast, have an extremely easy first day and step up your schedule to (hopefully) sleep through the night which becomes the hardest parts in later days. Also it assures that your timing for each 24 period comes right around the start of the day, so if you have a troubled night and can’t go on, you can break it first thing in the morning with a full day complete. Ghrelin’s last trigger was morning, so it’ll wake you up (if you get sleep in the later days) but not when you are trying to sleep.
Late Evening gives the most normal feeling as you can have dinner around 4-6PM, but won’t really feel like you’re fasting until late afternoon the next day because you ate, slept, and just skipped a meal. However because your timing is around the evening and that will be when the last ghrelin spike comes so that might make you hungrier and cause you some expedited insomnia in the earlier days. Also to get an even day of fasting you do have to wait through the whole day to the evening, which can be taxing if you didn’t sleep the night prior.
I wouldn’t know what’s best but I usually start around 10am or noon because is usually when my eating window opens so is easy to keep up with the routine. That way I have time to hydrate before eating something.
This was my first, I started after dinner. In the future I’ll probably start in the afternoon, I tend to be hungriest between 11-1600 so I’d finished my afternoon coffee/tea/apertivo and start the fast.
As stated, it’s def easier to wake up “in it” if I have to talk myself out of coffee lol