How long do you have to wait to watch a new show on itunes after its aired on cable

Depends where you live and what Apple have negotiated with the content providers.

Sometimes available next day other tim weeks, longer or not at all.

eg Dr Who usually available to buy a week after airing in UK, but next day in US which baffles us.

eg Game of Thrones unavailable in UK as there is a deal between HDBO and Sky satellite