Should you? Yes.

What you should do? Whatever seems fun, I suppose.

I may have a potential idea for ya, But I'm much to shy to post it here especailly since I'm not 100% on the details >.<

It's brainstorm time, so nothing is set in stone!

well, if I recall correctly from our chats, Iri, at least the big'un, has 4 cocks, and 2 tailholes yes? I was thinking keep things a little subtle and have a picture with Iri on their side, fully erect and either wearing a strapon or having a sildo in front of them (so 5 cocks) and showing both tailholes either on their own or with plugs inside them with a ø symbol on each for two zeros.
AKA. 5 0 0 or five hundred! it's not so flagrant that the image is pretty much ONLY good as a celebration of a number milestone, while also being possibly visually appealing as a whole, though the subtler number showing might be lost on some

alternatively just could get a pic with a milker and something stating that "you've produced 500 gallons/litres this session, good job! we'll bump the production quota up next time"

Do what you feel yo