That timing was because Jubilee is the newest ship and attracts more Platinum and Diamond cruisers, which reduces the number of FTTF slots available. Other than Journeys cruises, where they don't sell it, FTTF is going to open up much sooner on ships that aren't the latest and greatest.
With rooms no longer being immediately available upon boarding, and with FTTF priced so high how, I wouldn't worry about it selling out on most older ships.