You should turn your rig on and listen to it IMMEDIATELY before it gets too warmed up, and then turn it off after a few minutes and go away. It doesn't necessarily sound better, but this forces you to get out more.
Seems like the best "upgrade" for tube amps....
...is to leave the amps on for a few hours before playing. I've noticed recently that when I turn on my Joule amps and let them run for hours, it makes a huge difference in the dynamics and high end sweetness. It gets hot in our house, but it's worth it. Is there a technical reason for this?