How do I tell if a gift that arrives is intended to be for my engagement, shower, or wedding?
It’s all about timing. Gifts that arrive soon after your announcement are probably intended as engagement presents; toward the middle, as shower gifts; and close to or after the ceremony, as wedding gifts.
But for the purpose of thank-you notes, the occasion doesn’t really matter. Your note should reflect your relationship with the sender and your feelings about the gift, not the occasion it commemorated. “We broke in the blender with a banana smoothie on Sunday morning, and our relationship has been sweeter ever since” works fine, without any mention of your wedding.