You have to add tags before favoriting article (or before IFTTT checks for updates). Otherwise, these all go to "Unread" in Pinboard anyway, so I scan that section for links that don't have any tags from time to time.
Then
Add read later bookmark
This Action will add a new bookmark to your Pinboard account to read later.
ID dcDPQxeY
Discover more time saving integrations for Pocket and Pinboard