Are there more than 4 people in your party? As in, will it require 2 tables to be put together? Are you willing at accept a table inside, or are you going to ask to be seated outside? What time are you planning to check in for a 12:20 ADR? I'd pad it with 15-20 minutes to be seated, then another 20-30 for your food. The last thing you want to do is to be rushing to eat if something takes a little longer than ideal or be rushing to check in for your tour 15 minutes before it starts. I'd probably do noon, hoping that everything would take an hour and 15 minutes, but leaving an extra buffer, just in case.