Submitting future research plan when intending to leave
Think about the worst case that can happen if you do/do not tell them. If you do tell them and none of your interviews results in a job offer, you're seen as someone who won't be around for long, in whom it is a waste of time and money to invest, etc. It's going to be detrimental to your continued career if you tell them that you're thinking of leaving unless you are certain that you will. On the other hand, if you don't tell them now and leave later, you're certainly going to annoy people in your current department and you may burn bridges, but by then these will be your former colleagues who will not be able to influence your career any more at that point.

So, if I were in your position, I would wait.