Time & Date Value

Time & Date Value

What is the value of time and date in the system?  I am trying to update some timed fields in requests, specifically the scheduled_time value of on hold.  how do I generate the numeric value for the value field from a date time picker or the conversion of a specified date and time.

"scheduled_time":{
     "display_value":"Tue, Sep 8 08:00:00 EDT 2020",
     "value":"1599566400000"
}

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