Show modal only if someone is new / reset after 30 days

I’ve added a modal to my site and I’m trying to get it to only show the first time a visitor comes to the site and no subsequent visits based on the cookie, but I can’t figure it out. Also, I’m self-taught, so I have a bit of a hard time understanding some of the js and custom code. Any help is much appreciated!


Here is my site Read-Only: https://preview.webflow.com/preview/ossiamarketing?utm_medium=preview_link&utm_source=designer&utm_content=ossiamarketing&preview=bc163e6c393164efbc45a6854509d8ff&mode=preview