This is a pretty common complaint, I've seen numbers as high as 18-20% feel some sort of pressure, and upwards of 50-60% of those people feel enough discomfort that they don't use ANC.

I feel pressure almost immediately but it doesn't the level of even mild discomfort until 7-8 hours of continuous use (my employer provides a pair that have an ANC option). Even then I can deal with it for longer if I'm watching a movie or something after work.