Actually, the current plans are not to have a paying cruise from Europe to the U.S. The Oasis sailed from Europe to Florida with no paying passengers. The current plan is for the Allure to do the same thing as Oasis did - media hoopla 1 and 2 night cruises once it arrives in Port Everglades, followed by the first revenue cruise of 4 nights to Labadee and back, and then the first 7 night cruise cruise which will be considered the "inaugural" voyage.
This could change of course, but at present the OP will not be able to sail on Allure from Europe to Florida.
I think RCI wants to make sure the Allure is "ready" and they don't want to have the problems encountered for the first many sailings of the Oasis - water shows not ready, cabins and public areas still being finished, etc. When I boarded the Oasis for the first revenue cruise they still had stacks of cardboard which had held lamps sitting in the Promenade. 3 days later I stumbled over sheet metal which was still being installed for baseboards and overheads. RCI doesn't want to see this repeated, and they won't risk it by selling a transatlantic cruise which might prove embarrassing.
I was thinking of the Norwegian Epic and her doing a revenue cruise on the way to NYC when I posted my earlier comments. Of course now NCL is under some new pressure given the fire which destroyed an area on the Epic the other day. The shipyard still says they'll meet the delivery date.
Last fall Royal Caribbean had a deal with ABC and Good Morning America which no doubt was worth a lot of money. I can't see a similar payout for exclusive rights to the first media reports of the Allure, but who knows? I do anticipate some hype as the Allure leaves Europe, with daily videos from the ship and some sort of build-up on a morning show. RCI tends to stick to the script on these things. For instance they did a big production with the Today Show for the Freedom Of The Seas debut, and did a similar but smaller deal when the Liberty Of The Seas came out.
Whoever gets the rights, I hope they don't blow it like Good Morning America did with the Oasis. They did a horrible job and whoever was responsible for the production ought to be ashamed. It was total incompetence.