Free Apple TV+ with purchase of iPad Pro

The free trial must be claimed within 3 months of setting up your new iPad; also it is no longer for 1 year. See the information in https://www.apple.com/promo/pdf/EN_US_ATV+_Promo_TandCs.pdf

The AppleTV+ trial is a one-time offer applied to your AppleID account. 

Whilst the offer is linked to the purchase of a qualifying device, ultimate eligibility is determined by your AppleID. If you have never previously had an AppleTV+ subscription, purchase of a qualifying device provides an opportunity to try the AppleTV+ subscription service, free; the offer must be redeemed within 60-days of initial activation of the qualifying device.

If you have at any time previously had an AppleTV+ subscription, under terms of the offer (see the small-print), you’ll not be eligible for this offer. Cancelling your current AppleTV+ subscription will not reset your eligibility - but will immediately cancel a paid subscription and lose access to content for the remainder of the period for which advance payment has already been made.

The AppleTV+ trial offer was originally for one-year - but from 1st July was reduced to three-months. You can check eligibility here:

https://offers.appletvapp.apple/tvp01213mf