To use Widget["Timer"], you first need to load GUIKit using Needs["GUIKit`"].
Widget["Timer"] is a useful nonuser interface widget that creates a timed action that you can bind calls to. It can be started and stopped, and its "delay" property in units of milliseconds can be changed while it is running.
The following properties are available:
"delay"
the time in milliseconds between events
"initialDelay"
the initial delay in millliseconds before the first event fires