The champions of the Temporal proposal are looking for people to try out the polyfill we have published and give us feedback so that we can make sure that we have a really good API before asking for a Stage 3 review.
To try it out casually, with an interactive prompt, visit the API documentation in your browser. On any of the documentation or cookbook pages, you can open your browser console and Temporal will be already loaded, ready for you to try out the examples.
On the other hand, if you want to see what your project would look like if you ported it to Temporal, you can
npm install proposal-temporal and start porting. (Do note that you should not use the polyfill in production! We plan to change the API based on the feedback that we receive during this period!)