Halloween themed "party" in September??

cc

Sept 20th we are planning to have a small welcome baby party. Since it's our 3rd child we dont want to do anything formal or ask for gifts but just for family to come hangout and eat food and bring diapers if they feel like bringing a gift. I'm due Oct 27th so I was thinking about doing some silly little treats and decorations like these. Is it weird to do halloween theme in sept??