odoo 12 enterprise

I try to setup a simple task in Automation Marketing

is after i send an Estimate/Sale Order to a clients an email is automaticly sent after 7 days to this cleint about the estimates we sent.

i try to filter using a specific task as a trigger

but i need to send it after 7 days, and i need to filter if the email was already send, dont do it again.

any idea what filter or condition would be apply ther ?