rehearsal dinner ?

I'm getting married in a church on a Saturday afternoon in March...
how do I know when my rehearsal will be, so that I can book a place for rehearsal dinner?


Probably a simple question...but...

thanks
Jess

ETA: i've called the church numerous times withthis question but it never seems to get ansered....

My church called me about 4 months before the wedding to schedule the rehearsal. They gave me the option of Wed, Thurs, or Fri either 6 or 7pm. We chose Thurs the 21st at 6pm. We booked the restaurant probably 2 months prior to the wedding. If it were up to me and NOT the Future In Laws it would have been sooner but we got the room we wanted anyway.

in-laws aren't organizing or paying for RD
FH and I are doing it all...
May parents have done so much for us for our wedding, that I didn't want to add this expense onto the list....

and let's not get into the in-law issue..