Unfortunately this isn't an option with Recurring Payments. The amount of the first purchase is the amount that recurs. So if they're charged $0 the first time, that's what they would continue to be charged. Also, the Recurring Payments add-on only allows for payments to recur on a monthly or yearly basis, so they wouldn't be charged until at least a month after their initial purchase, not just 3 days.
Let us know if you have any additional questions.