Too late to negotiate terms for an internal move or time is now?

BLUF: I'm about to make a move between departments which is theoretically a promotion and have been offered a very low increase. Am I in a position to negotiate? I've edited down from my original post now that I am clear on my actual question.

I discussed an internal move some 9 months or so ago which we agreed would take place subject to transition. I finally received an offer letter at 3pm Friday for my starting today (Monday).

Until Friday I wasn't in a position to negotiate terms as I had not been made an offer. Am I too late to negotiate? I realize (from the podcasts) that you can't negotiate until you have the offer. My dilemma is that because of the timing of the offer being received, I have already moved and announcements made.

The whole scenario has used up a huge chunk of goodwill on my part. My new boss didn't even speak to me about the offer, just dropped the letter on my desk and made a hasty retreat. The rise is also so low that I would have been less offended if I'd moved across with no change, especially if someone had actually spoken to me. The timing alone has left a sour taste in my mouth because at a time when I should be excited and preparing for my new role (which I am delighted with) I can't avoid thinking about this.

I'm seriously hacked off but at the same time don't want to start off on the wrong foot with my new line management.