Javascript/HTML Short Custom Code Needed

Hi there! Quick fun project. GOAL: Make a website page redirect x hours after an email is sent. CONTEXT: We want to email our users a flash sale link that expires x hours after the email is sent. The challenge is that everybody receives the email at different times depending on when they opted in to the email list. This means that each user needs a unique expiration time. Must be achieved with front end code (HTML, Javascript), since that's what the website builder gives us access to. I'm thinking that the way to do it may be a unique URL for each user with date/time parameters appended to it (somehow we could append these automatically with Mailchimp). Then perhaps the page could have some code that redirects the user if the current date/time is after the date/time in the URL the parameters. I don't know if this is the best solution - just an idea. For a knowledgeable programmer, this is probably easy. I hope so! Please confirm that you believe you have a good solution and the amount of your bid. Thank you!