How do I get a list of tasks that were created after the issue which it is linked to?

[Horea Pauna]

I have tasks that are linked to issues but some of them were created prior to the issue.

I get all of those using the following filter: 

issueFunction in linkedIssuesOf("labels = X")

I only want to know which tasks were created as a reaction to the issues with label "X"  and remove tasks that already existed prior to the issue being created. 

I want to get a filter that allows me to view tasks that are linked issues of label "X" and were created after the issue.  

The goal is to see how much new work was generated by the issues I create.