FWIW, I tried to make online ADRs at 6:15 am and kept getting the "system too busy" message. Picked up the phone at 7:03, got an operator within a minute and had my ADR booked for pre-marathon-pasta Tony's Town Square by 7:06. Still couldn't get in online. So, I'd say be on the computer and the phone if there are hard to come by ADRs that you're looking for. Wasn't going online supposed to make this easier?