How long does it take a paypal payment to go through?

I have tested the form and made a payment through paypal, but on the "My Forms" page it says it there are no submissions and that my submissions is "incomplete", even though I received an email confirmation from paypal saying the payment has gone through. 

If your forms payment are going through but the submissions are still being marked incomplete, you may need to enable IPN in your PayPal account:

http://www.jotform.com/help/276-How-to-Enable-IPN-for-Paypal

IPN (Instant Payment Notification) is a POST message sent by Paypal (for regular merchant accounts) whenever a transaction is completed on their side. This message contains all the data regarding the payment transaction completed by a form user.  If this is not enabled, the message that the transaction was completed will not be forwarded to your JotForm account and will be marked incomplete:

http://www.jotform.com/help/564-how-to-view-incomplete-payments-of-your-payment-forms/