Survey flow logic based on Date

Hi Qualtrics community,
I have an on-going project in the EX Engagement Survey platform that I would like to set the survey link to expire after a certain period of time, so that people cannot take the survey after a certain amount of time since they have received the invite (I couldn't just close the project because we are sending out invite in bathes, and it could take a few months for the entire company to finish data collection).
I am only trying to do this after learning that there isn't a default survey link expiration time in the EX platform (correct me if I am wrong here, I learned this from Qualtrics Support).
After some digging, I couldn't find a way to set the link to expire, so I thought I could set something up in the survey flow so that if people attempt to take the survey after certain days have passed, it automatically take them to the end of the survey. I added a "Send Date" metadata to all the participants, and told the survey to capture the date (minus 20 days) when the participant opened the survey. Then I tried to set the logic to be if the "Send Date" is greater than or equal to the captured date-20, then they are recent enough invitees and they can take the survey. Otherwise (less than the captured date-20), they have waited too long. Shown below (this is a test project just to test the concept):

However, I could not get this logic to work. I thought it may be a formatting issue with the date, but I have tested multiple different formats, and nothing worked.
Would my method work? What did I do wrong? Or better, is there another way to achieve what I am trying to do?
Thanks for your help!