bugfix getting first layer

dist/L.TimeDimension.layer.weather.js

@@ -339,7 +339,7 @@ L.TimeDimension.Layer.WMS.Picasso = L.TimeDimension.Layer.WMS.extend({
         },
     
         _getLayerForTime: function(time) {
-            if (time == 0 || time == this._defaultTime || time == null) {
+            if (time == 0 || time == this._defaultTime || time == null || this._refTime == 0) {
                 return this._baseLayer;
             }
             if (this._layers.hasOwnProperty(time)) {