Capture campaign data 7 days after send

Hello - this may seem like an easy question, but I can't figure out the answer. I'm trying to capture campaign data from 7 days after the campaign was sent. Everything I've found includes current date and going back which would make the report dynamic and not lock it in to the 7 day window. I'd like to use the start date and look forward 7 days regardless of when you are viewing the report.