Paying your self back IVC question

Hey everyone. New to IBC. Looking to open up a WL policy within the next 6 months. Currently I’m am 29 and my wife is 23 and we make about $300k annually.

My question is after researching and watching YT videos lots of people say that you “pay additional interest just like you would on a normal loan” on your policy loans through PUA. Do these PUA get added when you open up a policy or can you add them at a later date?