Attacks or invasions are often better if the timing is postponed.
An attack may have a much better chance of killing if you wait and get a few more stones in place. Even if killing isn't the objective, the correct direction of play for an attack can become much clearer over time.
An invasion is always likely to give the opponent some extra influence. Early in the game the trade of territory and influence may be unfavourable for the invader.
See also let the enemy off in order to snare him.