Slow down.
First, you would be very stupid to ship before your customer has paid and his payment has cleared.
Then, Paypal holds cleared payments to new sellers, sellers in high fraud/high value categories for 21 days and to sellers with poor selling practices against the seller's good performance. This is not negotiable. It is a Buyer Protection.
However, once your customer's payment has cleared, although PP will be holding it , you will be able to print a PP shipping label and the payment for that will come out of the held money. So there is no reason for you not to ship promptly after your customer has paid.
Small bonus, there are discounts on postal costs (between 5% and 18% off PO counter prices) when you use PP shipping labels.
