Are transporters meant to be used single handedly?

If I recall correctly there seem to have been a number of occasions where people have been able to initiate a ship’s transporter themselves and then get on the pad quickly enough to safely transport away.

Is the small delay which gives them enough time inherent to the transporter, or can they control this setting?

It usually seems that the transporter, when operated normally, starts to transport as soon as the operator engages it.