Benchrest shooters know that recently sized brass shifts. The greatest change occurs within 30 minutes of sizing but it continues to change for about a week. These changes can affect accuracy. All BR shooters load all of their ammo at least a week before a match. You should follow their lead.
Every single statement in the preceding paragraph is wrong, it kinda hurt to type it but it was fun.
BR shooters take 20 rounds to the line, shoot a target, go back to the barn, wipe off cases, neck size and decap, prime, charge, and seat a bullet then take those loaded rounds right out and shoot the next match. They do that so they can adjust the load to conditions. If they had brass that they prepared and fireformed last winter, there would be zero change to the procedure. Brass doesn't change size.
You can find all sorts of crazy shit on the internet. There is a thread around here somewhere on "stupid shit I heard" - brilliant. My personal favorite of the hour is, "moly coated bullets are better".