When I started I did 20 minutes twice a day. After sometime switched to one 40 minutes chunk.
Noticeable results came after 1 month of training. After month 2 my understanding of things, clarity of thought, articulation became much stronger. After month 3 my thoughts became more complex, sometimes almost multilayered. I started yo have strong urge for complex patterns and subject and also a despisal towards some primitive stuff, like in music and books. Now I'm on some plato again and feel this miz of curiosity, agitation, irritability. Like my brain almost itches sometimes, like it's being electrically stimulated or something.