It is an important part of event planning that is usually carried out at its beginning stage.
When organizing a scientific conference, for example, organizers might take into account the knowledge in which periods classes are held at universities, since it is expected that many potential participants are university professors.
They should also try to check that no other similar conferences are held at the same time, because overlapping would make a problem for those participants who are interested in attending all conferences.
When it is well known who is expected to attend the event (e.g. in the case of a project meeting), organizers usually try to synchronize the time of the event with planned schedules of all participants.
In such cases, the organizers should first define a set of suggested dates and address a query about suitable dates to potential participants.