I’ve not tried the earlier than ADR asking. But that said, I noticed 2 instances where there seemed no wiggle room at all re ADRs.
At SciFi we had ADR lunch & got seated pretty quickly. I noticed people coming by, asking to be seated standby &/or earlier. They were told to wait & see. I never saw them enter the restaurant, so I’d guess they had a pretty long wait.
At Coral Reef dinner, we were over 15mins (the “allowed” , sometimes) window for lateness haha. We were told they’d seat us at next available table. One hour later (yep, that’s one hour, folks) we were seated. If I’d known the wait was that long, I’d have tried to schmooze a waiver of the no-show fee, and find another place for dinner.
So I guess what I’m saying is that many of Disney’s restaurants don’t have much opportunity for earlier (or standby) tables.
The tip, stated above, re trying for an earlier ADR 1-2 days before your ADR is a good one. Lots of folks hold on to a bunch of ADRs & cancel them within the 24 hour window, to avoid the no-show fee.
I’ve also used the Touring Plans reservation finder, with success, to move up the time of our ADRs. We’re a fam who likes to have dinner early in evening, around 5 or 6pm, and those times are often hard to get. They seem to open for availability a lot more,the closer we get to our trip week.