Personally: wipe down with Ballistol every time, run an oily patch every 500 rounds or every year just for storage, scrub the bore with the copper brush only if it needs it- I think I've done the one I shoot most often once in the last 5 yrs and there was maybe 5000 rounds shot through it by that point. That would be minimum to me because that is what has proven satisfactory. However, I've also only shot copper jacketed bullets through my .22s for the last ten years probably. It is my understanding that scrubbing a bore too often does more harm than good.
Also, I would strongly recommend a Dewey cleaning rod, they are nylon coated steel so they are stiff and strong but will not damage the bore. Not cheap, but good quality and will last.