Consequences, both desired and undesired, for the very young (even the very bright) must be immediate. For a two year old, anything beyond a minute is almost worthless. They have great difficulty connecting a delayed consequence with their behavior. For a four year old, anything beyond two to three minutes is almost worthless and at that, you almost have to give them some kind of signal such as a timer to let them know when the positive consequence will occur. If it’s an undesired consequence for inappropriate behavior the weight of the immediate reward (if gained by inappropriate behavior) will far outweigh a delayed undesired consequence for almost any young age.
As children grow into adulthood, they can, if properly taught and if typically developing, begin to understand delayed consequences. For example, most adults are able to work and understand that they will be paid weekly, by weekly, monthly, and in some cases at the end of a contract. They also learn to understand the more immediate rewards for work and good decisions and hopefully they (we) learn to understand the value of delayed consequences.