PHP Timer-timed task sleep does not execute after refreshing the page

PHP Timer sleepphp

is also a customer's wonderful needs, need to do a timed task in PHP, in n days after the execution, I found on the internet is using a while loop, inside with sleep () to control the task start time, but the problem is that the page before the start time can not jump, if I write jump to sleep () before the words , sleep will not be executed.
In fact, the most headache of the problem is mainly in sleep execution when the customer can not do anything else, and the customer needs a regular time is very long, almost 4 days of appearance, so want to ask if there is no other way

