At my home church, we have our main rehearsal on Friday nights, at which time we practice the songs we will do that coming Sunday, the songs we will do the Sunday following that, and any new songs or other material we need to work on.
We also have a short practice on Sundays right after service, just going over the songs we will sing the following Sunday. I would love to have practice right before Sunday service instead of right after, but the downtime between Sunday School and Morning Worship is too short to make that work.
So when the time comes to sing a song in service, we have practiced it 3 times (two Friday nights and one Sunday afternoon).