My pre-order from Verizon of the S20 FE has had the promo approved by Samsung. I assume this will be the case for the other carriers, too.
Download the Shop Samsung app from the Play Store (or Samsung Store probably), pull out the left side menu, and go to My Inbox. You’ll probably see the promo ad there and a link to check for eligibility. You’ll need proof of purchase of some sort (shipping slip, invoice, email, etc.) that shows it was ordered during the pre-order window.
Mine was approved in less than 12 hours.