Found a neat and simple solution to the need to capture and pass today’s date into a custom date field, to allow a campaign to test and branch based on the date. Today’s date is captured and submitted via a hidden input field in the order form.
Where StartDate is the custom field created in Infusionsoft.
Referenced via Contact0_StartDate.
All credit to StackOverflow for the solution modified for this use:
In the order form you insert this code in the Product Area custom HTML section.
Hope this helps someone.