Question about HP Laserjet 4

I've wondered about this for years and years and would appreciate
commentary:

I've had this printer since 1994. This printer predates Energy Star
printers and doesn't have an energy saving mode. Even when idle, if
powered up it uses over 80 watts, possibly 100. Inasmuch as I print
infrequently, I turn it on when I need to print and then turn it off.
After printing even a single page, the printer makes a lot of noise for
about 20-30 seconds, and I presume this is a fan that cools some
componentry. I've always figured it might be best to wait for that noise
to stop before switching off the printer. Should I continue to do that
or can I simply switch off the printer when the last page (or single
page) has reached the exit tray?

Thanks for your comments.

Dan
.