I earned the puffin island before the time was up but it hasn't appeared. What can I do to get it?

First make sure you have the most current game update. Then tap on Orchid Harbor which is just southwest of your bush exchange boat. That should bring up the options of "empty", "sailboat" (if you earned it previously), and "puffins". If the puffins option is not there, contact customer support through the "help" button in the game settings (green gear icon) and provide your game user id as written under the "help" button.