In summary, we have a form on our website and when someone completes the form they receive a unique quote number. It is this unique quote number that we use to create a custom variable. If the customer returns to the site they input this unique quote number to show their details. The customer may return on more than one occasion (sometimes on the same day, sometimes on multiple days) and input their quote number.
We need to identify the first time/date the customer received this quote number, if this is possible?
Are you using DTM on your site? If so, you can create a data element that uses a CCS selector or JSON to retrieve the value from the page. You would want to also create an event-based rule that is triggered when the forum is submitted. That way the data element would be called when the forum is submitted and the value would then be stored in the data element for use in whatever call/code you'd like.
let me know if I can provide additional details or clarification.