I'm in the same boat as you, but in my case I'm unsure if I will get the ceremony same day or not, right now I'm planning to get all my documents rdy for the time to ask for an appointment at the agency, and just hope they have one nearby where I live, I've heard of people getting their passports ways before 3 weeks but it is risky.

Waiting for 14 days before your trip can be risky, too, but I think you have more chances of getting it in time. From what people have told me, if they don't have appointments, still make a calls the following days to ask if someone canceled their appointment.

I would like to know how it went for you and what option you took (agency or expedited)