New customers will be charged their first payment instalment at the time of purchase, and Afterpay will automatically deduct your next instalment from your nominated card every fortnight over the remaining 6 weeks.
You are no longer considered a 'new' Afterpay customer after you have fully paid your first order and 6 weeks have also elapsed since making that first order.
Existing Afterpay customers will have their first instalment deducted 2 weeks after placing an order, with fortnightly payments, and the final 4th instalments 8 weeks after making the order.
At any time you can log in to Afterpay and view your payment schedule - you can also choose to make a payment before the due date, otherwise Afterpay will automatically deduct the instalment from your debit/credit card.