This query is working, but i am not able to find out how to filter it on Created Date. I want Pull Requests which are created today. 

query GetPullRequest {
 viewer {
  name
    organization(login: “MyOrgName”) {
     name
           repository(name: “My Repo Name”) {
           name
           pullRequests(last: 10, states: OPEN ) {
           nodes {
                   state
                   title
                   permalink
                   createdAt
                  author {
                           login
                           avatarUrl
                 }
             }
          }
       }
}
}