I've noticed that people say that the upgrades sometimes clear a few days early, 2/4/6. Does this happen on CO too? It's happend to me a few times, but only on NW operated flights.

2. If I booked a reservation with CO, but NW has codeshare on the flight and i'm a NW elite, do I check the F bucket for the NW flights or since I booked it with CO, I look at the F buckets for the CO flights?