Google Stadia's service will launch on November 19, 2019 with streaming available starting at 9 am PT/5 pm BST that day.
Stadia Founder's Editions and Premier Editions will start being sent out in the order in which they were bought, and you'll be sent an activation code when your package ships that lets you set up you account and Stadia Pro, which you'll have access to for three months. It's normally $10 a month.