Hey there - if you have any tokens minted from your contract, including those via Claim pages, before Jan 2 @ 12p ET, then your collection will be eligible for creator royalties on OpenSea.
If your contract has no tokens minted on it whatsoever – perhaps you have a Claim page set for a future drop date – then for peace of mind you should mint a first token on that contract (can be a blank token that you can update later). Note: the token must be minted to mainnet.
To be sure, you can simply check your OpenSea profile and if you can view your collection and there is a token on OpenSea today (or before Jan 2), then your collection will be eligible for creator royalties.
Hope that helps.