Origanaly, in Feb we bought our VWL points. At that time they wanted $500 down, in full.
When we added on VB in this May, they wanted a 10% down, in full.
I am not sure if the down payment difference was due to a policy change, or because it was an add-on.
Ask your guide, as I have "heard" that as long as the process has started by that date, you are okay for the lower price. I am not really sure how true that is.