Try this query:

{

  me {

    id

    time_zone_identifier

  }

  users (ids:[29417812]) {

    id

    time_zone_identifier 

  }

}

It give the timezone for the current user and a specified user:

{

  "data": {

    "me": {

      "id": "29417812",

      "time_zone_identifier": "Europe/London"

    },

    "users": [

      {

        "id": "29417812",

        "time_zone_identifier": "Europe/London"

      }

    ]

  },

  ...

}

Thanks David 🙂 🙂 🙂