I don't understand the problem then.Basically immediately! I collected it from the post office with my friend, and she opened it whilst I was driving home. She spotted the first hole on the right side of the chest straight away, and asked me if the dress was supposed to be new (and it WAS supposed to be BNWT as stated on the listing). I got home after in 10 minutes, and checked the rest of the dress and found another huge hole on the hip. After I did my research online to determine authenticity, I sent the seller an email through eBay stating that there were holes and that I thought it was non-genuine.
My letter expressing my concerns was sent probably about an hour after I received the dress by post (PayPal can check the tracking + timing). All the seller said was that if I wasn't happy, to return it, and he would give me a full refund.
The listing does show a dress with tags so it's possible that the seller didn't notice the holes before sending it. Sellers are human and it's perfectly understandable that they might miss a flaw.
But if, as you say she offered a full refund upon return of the dress, why don't you just return it and be done with it. She did the right thing when contacted. I don't consider that to be a scam.