I waited until I had the plug in hand before I took the sideplate off my 638, to do the job all at once. If you feel you must remove the locking feature in order to completely eliminate the possiblilty of an unintended lockup in case you have to shoot the gun before the plug arrives, it probably would be prudent to remove all of the parts so there's nothing left that might come loose under recoil and jam things up.

It also avoids leaving something on the gun that looks like a lock but doesn't actually do anything when you turn the key. Obviously YOU know the lock is nonfunctional, but if you drop dead before you get the plug installed, your estate might end up selling the gun to an unsuspecting buyer who thinks he's getting a lockable gun but is later surpised when one of his kids makes it go bang. If that happened, you just know he's going to go looking for somebody to sue, and defending a case can be ruinously expensive, even if you ultimately win.

Better to have a hole in the side for a while (if you can't wait for the plug to arrive and feel you have to do something now.) People have been known to put a piece of tape over the hole to keep small critters and cookie crumbs out, if that's a concern.