Stale HTTP requests firing after OnResume

I have an application in which an HTTP request is sent to a web service every 12 seconds.This request is time sensitive, meaning, it has to use the latest time stamp to make the request.

Somehow, when the app resumes after a pause, a request with an old timestamp is being fired off, before a current timestamp request is sent.

How can i ensure that the stale information is not used?