[aprescott]

I was somewhat surprised to learn: it's available immediately. 2 minutes after they posted on Twitter that it's now available to everyone, I followed their steps of closing Tasks and Chat windows, hit refresh, clicked the link. Done. (You may need to be on the Rapid Release track.)

[hasanove]

I also had to close Tasks in bottom right corner, to see a button to switch to new design.

[patrickod]

Wow I didn't realise Google had changed their tone RE: Apps users. Brilliant