One of the things that I frequently see, is arriving to a venue or ceremony site, and the wedding party has no idea who is supposed to conduct the rehearsal.

Ideally, the VENUE should provide a wedding coordinator. Someone that is familiar with the grounds, the standard order of a rehearsal, where everyone will stand, how they will walk for both the processional and recessional, and can help cue everyone when it is their time to proceed. 

Unfortunately, venues I am finding, do not always provide this service. It seems to be, that it is becoming more commonplace (unless it is a church), that couples are on their own, in terms of orchestrating the rehearsal. 

Officiants should always have knowledge of the official order of the processional and recessional, music cueing, and where everyone should stand and sit. However, this is not the job of the officiant to provide the service. Couples that are having a rehearsal, and particularly a large wedding party, where there is not a wedding coordinator present at the venue, should familiarize themselves with the standard rehearsal process.

With that said, I have conducted many, many rehearsals for couples that wish to leave that aspect to me. There is an additional fee of $50.00 if I am to coordinate the rehearsal vs. just participate in it.

When meeting with your venue, ask them if there will be someone on site the day of the rehearsal to coordinate it.