I agree with trying to get a last minute ADR the night before, instead of showing up the day of. Because you are asked to cancel any unneeded reservations on the prior day by 11:59pm ET, a lot of people cancel between dinner time and 11:59pm. During dinner is a good time. Their wallets just took a big hit, and more importantly, they're feeling incredibly stuffed full of food... uncomfortably so. They're having second thoughts about going to an all-you-care-to-enjoy dinner the next day. So you see cancellations start to take place around 7:00pm and remain steady all evening. Then from 10:00-midnight, there's a final push for cancellations as people make last minute decisions to change plans.
During my last trip, this was my chance to pounce. All evening, I would check the
MDE app. Ohana had been booked for months and I had given up all hope. But now, suddenly on my third try, a reservation for 2 opened at 6:45pm. I waited to book it, trying to figure out whether I could make it after my last FP+. I hesitated too long. Within 2 minutes it was gone.
I was unsuccessful four more times that night. Later, at 11:30pm, I found a table for 2 at 9:30pm. Nice! But was it too late for dinner? As my girlfriend and I discussed and agreed to take it, but the reservation was gone again!
Lessons: (1) check often between dinnertime and midnight, the day before, (2) if you see a reservation, don't think about it... just grab it within seconds!, (3) enjoy your meal!
We employed these lessons the next night, and that 'Ohana meal we had been trying to secure for months was suddenly ours!
If you want to practice this technique, you can even do it from home to see how likely an opening will come up for tomorrow night. (Just don't actually book the reservation unless you'll use it tomorrow! This is only to get a sense of your chances!) This was based on my anecdotal experience, and YMMV.