1,000https://www.cnbctv18.com/technology/elon-musk-x-rolls-out-x-money-to-more-premium-users-in-the-us-19932854.htm
"Elon Musk’s social platform X has expanded access to its digital payments service, X Money, to a limited group of premium users in the United States, marking another step in Musk’s effort to transform the company into an “everything app.” "
Sounds like not all US premium users yet, but there is lots of time before Dec 2027.
If limited group is all those US premium users who have verified their identities then that might be enough? No idea if that is the case though.
https://www.xmoney.com/sign-up
Shows "sign up" for some services as well as a "get early access" for Crypto invoicing.
Though I haven't found eligibility requirements
X Money ‘external beta’ will go live in 1-2 months, Musk says