Check the website every day. If you're logged in, sometime it will give you the upgrade price. If it doesn't, figure out the difference between the Classic and the Premium. A "good" price is $6-$9 per day. On one of my upcoming cruises, I got a Black Friday deal of $6 and on the other, I grabbed it as soon as it came down to $9 (the cruise is in 2026 and I'm sure the prices will go up by then.)