Clean the bore, then put about 100 rounds through it, and shoot for real accuracy after that. My Axis had to have 100 rounds before it settled down. My .308 FCP-SR shot not better or less after 100 rounds. It shot well from the start. You may want to do some kind of barrel break-in cleaning intervals as you go. (Regular cleaning, no JB Paste) I usually do some kind of break-in, but I think it is more ritualistic than productive, but I can't stop doing it. I mostly use the break-in to familiarize myself with the rifle, sight the scope, check things over and etc.

A break-in may be good for the 22-250, as you don't want too many long strings overheating the barrel. Cleaning intervals will give you some barrel cool-down time. I have a 22-250 12FV on order as well. (My first rifle with that cartridge.) Due to the high FPS of the 22-250, many say go easy on shooting too many rounds at one time, or else you risk burning out the throat prematurely.