I am interested in learning the standard way of doing Delay analysis using a Schedule for claim purpose or time extension.
is there any template/ checklist that can be use for the said purpose
Try downloading the Forensic Schedule Analysis Recommended Practice from the AACEi website, no charge. This provides the framework for schedule analysis done in a claims situation (after the impact event has actualized or the risk is no longer shared).
Download the Change Management Time Impact Analysis Recommended Practice from the same site for a great explanation of how to do time extension requests.