Another way to check wait for Google Play Services & the map.

gistfile1.cs

var cancellation = new CancellationTokenSource();
Task.Run (async () =>

{
        while (true)
        {
            await Task.Delay(100, cancellation.Token);
            _map = _mapFragment.Map;
            if (_map != null)
                cancellation.Cancel();

        }
    }, cancellation.Token).ContinueWith(continuationTask => {

        DisplayMap();
        return;

}, TaskScheduler.FromCurrentSynchronizationContext ());