Generally speaking, a cold tappet setting is usefull for setting up a newly assembled engine to get it started.
Since your engine will spend the vast majority of it's operating life at normal operating temperature, this is really the best time to confirm that the settings are correct.
The "cold" setting makes an allowance for expansion when hot, but setting them hot gets it right on the money.

I'm trying to remember the old used car mechanic's line,...oh yeah
8 thous hot, 10 thous cold, an eighth an inch is near enough, the cars already sold.