Question about Costco discount– can I just grab one before making a deal or is that too new?

I’m not a Costco member since the nearest one to me is about a 45 min drive, but I could easily pick up a membership just for the discount. Does anyone know if the discount has a restriction on how new/old the Costco membership must be? I thought someone mentioned that there was a stipulation but I didn’t see a final verdict on it.