meteor where to put global tracker.autorun

I am wondering where to put a Tracker.autorun in oder to guarantee that everything else is loaded before. I thought that

Meteor.startup(function(){...});

is used for such situations, but when I reference the Geolocation object from mdg:geolocation it tells me that it is not defined yet:

Uncaught TypeError: Cannot read property 'lng' of null

I use the following workaround, but I hope that there is a more elegant solution:

 Meteor.startup(function () {
    trackerGeolocationInit = setInterval(enableLocationTracking, 100);
});

enableLocationTracking = function(){

    var location = Geolocation.latLng();
    if(location === null)
        return;
    else
        clearInterval(trackerGeolocationInit);

    Tracker.autorun(function () {
        var location = Geolocation.latLng();
        Meteor.users.update(Meteor.userId(), {
            $set: {
                "profile.location": {
                    type: 'Point',
                    coordinates: [location.lng, location.lat]
                }
            }
        });
    });
}

I'm writing an app for fun and this works:

   Tracker.autorun(function () {
      if(Meteor.userId())
      {
        var latLng = Geolocation.latLng();
        var userId = Meteor.userId();
        if(latLng &&  userId)
        {
          //do something
        }
     }
    });

No need to use interval. I simply put in a file call geolocation.js.