cimore, I think there is a bit of terminology confusion here. In this context, "paying upfront" means paying the full amount of the estimated cost of the course at the time you enroll.
What you are doing is usually referred as "paying as you go" and keeps both you and the training provider relatively safe and honest.
Whether you hand over cash or make a bank deposit or use a credit card is more or less irrelevant, except for traceability purposes.