Retrieve the next timestamp for an event.
(string) (Required) Action hook of the event.
(array) (Optional) Array containing each separate argument to pass to the hook's callback function. Although not passed to a callback, these arguments are used to uniquely identify the event, so they should be the same as those used when originally scheduling the event.
Default value: array()
(int|false) The Unix timestamp of the next time the event will occur. False if the event doesn't exist.