Most purchases are activated within 1-4 hours if you filled in the Username/Password box on the checkout page. If you did not fill this in, you will receive an email to your PAYPAL email asking for your desired credentials.
Setup emails will also be sent to your paypal email, but you can find everything you will need in the VIP section on the forums.
If you have not received any email about setup or credentials after 24 hours please submit a ticket with your payment email. You don't have to submit a ticket before 24 hours.