Your duty free alcohol will be delivered to your cabin on the last evening, by your cabin steward( at least that is what has happened on the several cruise lines we have sailed with.
There is an extensive range of duty free goods on board all the Celbrity ships, including cigarettes and alcohol. You could if you wished bring on 2 bottles of wine when you go ashore, just to drink in your stateroom but any other alcohol like purchasing on the ship is taken from you and returned the day before you leave the ship so you can pack it in your suitcases if you wish.
Can you bring two bottles of wine on board every time you go ashore ? Can they be 1.5 litre bottles or one 3 litre box per couple?