Changes to DNS entries entered via the zone file editor can by provided with an execution time. Thus you can schedule e.g. changes to redirect targets or the switch to a new hosting server to any date or time you like, perhaps after midnight or during a weekend, without the need to be present at that moment.
Of course DNS requests cannot be timed exactly to a minute. It is a good practice to set the TTL value of the relevant entries to a minimum value (such as 300 seconds) well ahead of the date the change is planned for. Together with scheduled execution of the actual change it will take place within a few minutes.
Imagine planning the lauch of a new website during a press event – using scheduled execution the new website will come up during your speech without the need of any manual interaction at that time!