I always flip 'em on and leave 'em on for 10-15 minutes. I only used the standby switch during breaks back in the day when we played as weekend warriors. When the tubes were hot they just sounded better. The old Fender Super got hotter and better as the night went on................ I also cranked it to 8 or 9 on the volume and used the guitar volume to adjust the level to where I wanted it. It seemed to be more touch sensitive that way.
Guitars
Wilburn Versatare, '52 FrankenTele(Fender licensed parts), Fender USA Roadhouse Strat, Fender USA Standard B-bender Telecaster, Agile AL 3000 w/ WCR pickups, Ibanez MIJ V300 Acoustic, Squier Precision Bass,
Amps
Ceriatone Overtone Special, Musicman 212 Sixty-Five, Fender Blues Jr., Peavey Classic 30, Fender Super Reverb, Traynor YCV-40 WR Anniversary w/ matching 1x12 ext. cab, Epiphone SoCal 50w head w/ matching 4x12 cab (Lady Luck speakers), Avatar 2x12 semi-open back cab w/ Celestion speakers
Pedals
Digitech Bad Monkey, Digitech Jamman, DVM's ZYS, Goodrich volume pedal