[gabbahh]

Taking notes is just good practice: it forces you to give more attention to your oppos.
Also instead of just playing the cards, taking notes is one of the first steps towards playing the players.
The more you move up, the more you need to play the players (as opposed to only the cards), so you need to learn the skill of reading player's betting patterns and other tells (B&M).
Therefore I believe it is never too early to take notes, even if they are simple ones.

Even though I am only a nano limit player, I spend a lot of attention to taking notes. Nothing sucs more then losing your entire stack against a tight a$$ nit who only goes allin with the absolute nuts, TWICE.