What he said. In my experience it does come back very rapidly, but immediately out of the gate is rough. Things we take for granted (like hearing your callsign in the radio garble) tend to be rusty and that can catch you off guard.

SIM is relatively easy (scripted vice real-world challenges) so best to warm up in a sim if possible.

If you're jumping into resource-limited (ie airline) training cold-turkey, best to get some kind of warm up first so you don't wind up with a PRIA event.