Yeah, that announcement is confusing. There is a bit of chicken-and-egg problem where clients and servers both need to add support, but each won't do much good without the other also supporting it.
I think the only shortlived certs they've made is for their own internal testing, and they even had a compliance incident involving some of them. I'm sure they'll open up testing in staging at some point, but I'm not aware of them having published any specific date or anything yet.