You are fortunate in that DJI uses smart batteries. In "THEORY" you could fully charge the batteries and let the smart batteries discharge themselves to "storage" levels". I wouldn't recommend that. I would charge them till I got the third light flashing then put them in a nice temperature controlled room in some fireproof-like container. I'd check them every couple weeks to make sure the DJI battery safety features didn't completely drain the battery.
My Phantom 4 can go several months between uses. I do as I said, charge till the third light is flashing then I put the batteries in an old steel ammo can and put it on my basement floor away from anything that might ignite. I've basically done this method for over 10 years with various lipos (RC planes, RC cars, etc) and have never had a problem. I've even goofed up years ago and accidentally stored a fully charged lipo for three years which swelled up so much it split the plastic case... Sure the battery was useless, but no fire...
That sounds like a pretty good method.
That's a strange feature they've built into the batteries whereby the discharge countdown resets if you press the button.
Can't think what the point of that would be ???