Why there is an hour lag time before I receive the customer jot form in my email?

There could be a temporary issue with mailing, but technically once a form is submitted it's almost instant like a few seconds difference.

I've tried it with my gmail account and it's receiving the notification instantly.

Please test it again and report back if the issue is persistent with your email. I would also suggest that you add Jotform emails into your contact list.

Guide: https://www.jotform.com/help/145-Whitelisting-JotForm-IP-Addresses-and-Domains

Let us know if you have any questions or if you need further assistance.