Some years ago I was cleared for takeoff (757) after a 747 at JFK, the controller was not satisfied when I did not start the takeoff roll 30 seconds after the 747 rotated and told me the next time when I was in New York I should advise the tower if I was not ready. This was a few weeks before the AA 587 lost its vertical stabilizer due to wake turbulence. 2 minutes after a heavy our SOP said. I did just that. I did not respond when he told me to change to departure and wished me a nice flight.