if a dramatic pole shift, how long would it take for the new polar region to start getting cold?

414 000 years
minimum

If the earth shifted its axis of rotation so that the USA was the new pole-in one hour- the resulting thermal energy would turn the entire crust to molten slag.

A planet of molten slag takes a long time to cool down.

As an example-take a metal spoon.Tape it to your foot.Now run it against the carpet at 1400 miles an hour for an hour.

even though i dont know the answer, i think youre way off

Not long,they found wooly Mammoths with food in gut
frozen in place.

was that due to a pole shift though? i thought it was something else that caused that, idk though

what else? what else can possibly transport animals with temperate plants in their mouths to a frigid zone, buried in frozen sludge?

the weather zones didn't just shift, making siberia cold, instead of warm. the only explanation is the planet shifted underneath the weather zones, and that was VERY recently geologically speaking.

i think pole shifts of a few degrees are a common occurrence

And there are 600,000,000 acres of green fresh-frozen tropical forests underneath Antartica. The pole is already moving 40 miles per year.