It depends on your definition of "playing with" :)
If you're happy to write code against the model and see how it type-checks to get a feel for things, then grab a main snapshot from swift.org and go ahead. The type checker implementation (behind -Xfrontend -enable-experimental-concurrency) is very close to what's in the proposal, with a few stragglers for recent changes.
If you want to actually execute some code, that's messier, because the concurrency runtime is still coming up. You can use the hacks from our examples (e.g., https://github.com/apple/swift/blob/main/test/Concurrency/Runtime/future_fibonacci.swift) to launch async tasks via a concurrent Dispatch queue.
Doug