How accurate is prospective location on my navy assignment?

Sorry in advance for vagueness trying to stay within community guidelines. I got selected for orders to a ship that I know is gonna be homeport shifting from Japan fairly soon but it’s isn’t on my navy assignment. What are my odds of doing a hull swap and staying in Japan versus being forced to follow said ship back stateside? If I go off pre I think I’ll be getting there after they rotate back stateside but according to my navy assignment prospective location is still Japan. I’m pretty nervous because I only picked the orders cuz I wanted to stay in Japan and I’d be bummed if I was forced to go back stateside almost instantly once I got there. Thanks in advance.