Remember to keep the trainer running the whole time you are playing and the unlimited cash button should stay 'Pending' the whole time too. The button changes to 'Pending' after pressed and stays that way until you either click it again or exit the trainer.
It probably doesn't matter as long as you wait and press the unlimited cash button until you have the game running (and probably until you are in your career).
I would start the game first, then the trainer.
