Easiest way to see if you have the year or a weeks free trial, is to go to the AppStore, tap your user icon at the top right, then tap on Subscriptions.
You’ll see Apple TV+ there and if you have the full year, your next billing date will be the 1st November 2020.
If you didn’t activate the years free trial at the time, you should get the option to do so again when you go to view an episode in the TV app.