I´d stick to the manual, but wouldn´t worry about a pop - at least it´s not unnatural.
But as long as you are aware of the correct routine, the amp is safe in your hands I think.
However, I find it strange that many people are lazy on the stand by routine, but still complain about tube prices.
It really is a difference, specially with tubes of a lesser quality.
I have built a 20w DR combo for our guitar player, and trained him to use the switch.
If he powers down now and forgets to use the stand by switch, he gets that frightened look on his face, like the amp is gonna blow up