Sadly all age verification slots were used up weeks ago, best bet is to keep track of official updates from VRChat either here or on social media for when the next round of slots open up. Also you can be directly notified when Age Verification Beta is expanded by opening this link: https://vrchat.com/home/ageverification
That said VRChat are looking into Age Verification potentially leaving Beta sometime soon but plans can change.
Source: Official VRChat Discord
Lastly while the thread is now closed the Age Verification FAQ can hopefully answer any further questions.