If I'm not mistaken many games in the
casinos operate with a 'not picking your cards up until all are dealt' rule. However I don't think this is an enforced rule in tournament play.
Personally, I always wait until it's my turn to act before looking at my cards. Firstly, so I don't inadvertently give off any tells myself and secondly, so I can spend the time whilst play is reaching me observing the other players as they look at their cards and act.
If I am first to act I wait until everyone has two cards dealt. I don't know why, force of habit perhaps...
A good tip along similar lines to this topic is when the flop is dealt don't look at the cards, watch the players. The cards will still be on the table for you to see a few moments after the flop is dealt and if you're staring at the flop you might miss visual clues from other players.