It’s not so much about what you’ve uploaded and when, but that you have legal age identification records available for anyone involved. Which is mostly normal, 2257 complicates things by spreading out the responsibility for who else needs those records and that changes depending on the back and forth legality of it all over the years. Like any legit video you watch or adult site you visit will have a little 2257 compliance bit that basically says we have the IDs of everyone in this video on file and available for law enforcement requests. But 2257 expanded that so anyone involved in the dissemination of that porn content are technically supposed to have those legal age identification records as well.

Here’s the Wikipedia article on it. You as a Creator would be a Primary Producer, but anyone that posts it to the site either hosting it on the site or using an img tag would then make themselves and the site owners Secondary Producers. It’s all a lot of grey areas and it was basically written to be used as like the internet equivalent of broken tail light enforcement.