If we observe our behavior, we procrastinate doing something good but we are in a hurry when it comes to doing something bad. For example if we are angry we want to express it immediately and not wait.
Do you know WHY? Because virtues are your very nature and they will never leave you. Your vices are not your nature and they will leave you. The negative tendencies are transient and they will leave you if you do not act on them. Frustration, crying cannot stay for long, at least with the same intensity. Perhaps we are concerned that the vices will leave us if we do not act on them.
It is only wise to postpone the vices for they will not stay and act immediately for doing good, otherwise we will keep postponing the good for the next few lifetimes. (Laughter!!!)