I'm aware that the deal is only for this weekend, but I'm not quite sure if it's exclusively "If you buy a Rift S RIGHT NOW" or "If you own a Rift S". I'd like to grow my VR library, but after buying the Rift itself: I'm running low on spendable funds.
If you've bought your Rift S very recently (in the last few days), you could ask support and they might give it to you, but it's not a "free for all Rift S owners" type of offer.
Edit: Actually, I don't even see any mention of the offer on the Oculus store when I add a Rift S to my cart, so I'm not sure what the limitations are, if it's only valid in the US, or what conditions might apply.