It’s status on check-in (or maybe day or two before) that counts. There’s no magic formula to calculate your chances of an upgrade. I did OLCI and chose a specific room, but still managed to secure a better room on physical arrival to hotel. They do offer digital key, but mine got confused with the front desk upgrade and offered me digital key to the original room. I suspect if you do OLCI and request digital key, there’s a good chance you’ll be in that room. Personal (and polite) interaction with front desk, in my experience, yields most chance of upgrades. Of course, if the hotel is full, your chances of upgrade are close to zero.