I found a list for the steps to take when powering up a new tube amp for the first time at 18watt.com. The origional post is here.

Before the first power up

• Trace entire circuit with hilighter
• Measure all resistor values
• Test all ground connections to each other
• Check all tube connections for poor solder joints
• Cont test adjacent pins on tube sockets
• Check all OT wire colours & connections
• Check all PT wire colours and connections (measure winding values)
• Check all ground connections (from the leads)

First Power Up

• tubes out
• output with dummy load
• on standby
• use variac slowly to bring filter caps up (for SS power supply)
• power on
• check voltages to transformer, heaters
• check voltages on rectifier tube - compare against schematic

Second Power Up

• rectifier tubes in
• other tubes out
• output with dummy load
• use variac slowly to bring filter caps up (for tube power supply)
• power on
• off standby
• check B+ voltages
• compare to schematic

Third Power Up

• all tubes in
• output with dummy load
• power on
• off standby
• check tube voltages - compare to norms.
• Also check line voltage.

Sound Test

• test with signal generator or guitar
• Exercise all knobs
• Exercise all jacks

Pre Burn-in Adjustment

• Adjust Bias on pre-amp tubes
• Adjust Bias on power tubes
• Calculate power tube plate dissapation