You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Doctor_Who

Context:
Only four episodes have ever had their premiere showings on channels other than BBC One. The 1983 20th anniversary special The Five Doctors had its début on 23 November (the actual date of the anniversary) on a number of PBS stations two days prior to its BBC One broadcast. The 1988 story Silver Nemesis was broadcast with all three episodes airing back to back on TVNZ in New Zealand in November, after the first episode had been shown in the UK but before the final two instalments had aired there. Finally, the 1996 television film premièred on 12 May 1996 on CITV in Edmonton, Canada, 15 days before the BBC One showing, and two days before it aired on Fox in the United States.[citation needed]

Question:
How many days was the 1996 film shown ahead of the BBC showing?

15 days