[In London at least, not sure about other places] Ranges from 20 to 40 mins of ads and trailers, although I've only heard of people complaining about the upper

[In London at least, not sure about other places] Ranges from 20 to 40 mins of ads and trailers, although I've only heard of people complaining about the upper extreme and never personally experienced it. Simple way out is to walk in to the cinema hall about 15 mins after the scheduled start of the movie - works for me every time.