We generally always book specific rooms, but for our upcoming New Year's Eve cruise we just booked a guarantee for our daughter and son-in-law's reservation. Our cruise departs December 30 and still no room assignment showing up on their cruise personalizer. I'm not very familiar with guarantee rooms, so hoping someone here can shed some light on when we might expect their room number to show up on their reservation.
Princess will assign you a room when it's convenient for them. TBH, the night before embarkation is the latest I've ever been assigned a cabin. I make it a habit to re-check my Travel Summary the night before a cruise to make sure that I didn't receive a upgrade (one can hope). Since I arrive at least a night before embarkation, I always bring a laptop so I can do this and print my luggage tags (either by accessing the hotel's business center or forwarding PDFs of the luggage tag to the hotel