That sounds like the show I saw in Missoula, but without Robert Cray.
The show started around 8:00 PM, with many excellent blues groups. The young couple in the seats behind us kept saying ‘Can’t wait to see John Lee, can’t wait to see John Lee’, on and off most of the night. Each had a bottle of Jack Daniels. By the time JLH came out to perform, around 1:00 AM, the couple had finished both bottles and were sound asleep. I couldn’t wake them up, it was lights out for them!