Question

When does the smell of hot cooked food reach you several with metres away within seconds

Answer 1

The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food youhave to go close because the kinetic energy of the particles of matter increases with the increase in temperature.
(The hot sizzling food's smell reaches us several metres away because food particles diffuse faster in air when hot and we smell it no time whereas cold food particles would take a very long time to diffuse and we have to go close to have a smell of it.)

Answer 2

Because of diffusion of gases. the hot cooked food mixes with the air and we get the smell of food with several metres away with seconds.