Hi kmk2016,
I received my itinerary from my travel agent I think we received it a few days before. I suggest making sure you get this before you leave so you know what to expect. We had a couple staying at the same resort as us and had no itinerary. They were told that the on-site wedding coordinator will provide it to her once she arrives but the WC was super busy with a current wedding that she was unable to do so.
In terms of changing itinerary, I'm not really sure. Maybe you could talk to the on-site wedding coordinator.
PS I'm super glad we did the BDR, it was very informative. Take lots of notes and have fun!!!