In a few hours on the NA server, the USN cruiser line will be realigned starting at T-6.
There are things you can do to profit with the split, such as making sure you have captains assigned to the ship (so they will be duplicated), etc.
Googling for advice on how to prepare will give you several recommendations on how to profit from it. https://www.reddit.com/r/WorldOfWarships/comments/7aaumf/uscruiser_split_what_to_buy_to_prepare_for_it_if/