Take time to tune up everyone in the band. If you do not know a tune that the band is going to play, chart it prior to the dance. If another backup musician knows the tune, ask them to help you. It is desirable for a band to chart all tunes in which the chord changes are not intuitively obvious or well known to all. This establishes the chording the band will use for the tune and prevents musical clashes by backup musicians all playing different chords.
Many tunes have more than one way that they can be chorded.
When the band settles on the chording it will use, the music will sound better. If the band reads music and uses music stands, the chord chart can be put on the stand. The chart also can be put on the floor and referred to as needed. Socializing, running through tunes, and obtrusive tuning while the caller is trying to conduct instruction or a walk-through can be very distracting, both for the caller and the dancers. Try to be as unobtrusive as possible until it is time to play.