Currently there is no golden puffle, so you need to wait, if it will come. However, there is a (fake) Golden Puffle in the Stage play "Quest for the Golden Puffle".
If they do make it, it will be right before the rainbow puffle. Due to some theorys, we are almost sure the Rainbow puffle will be the last made. The Golden Puffle might be too similiar to the yellow however, causing them not to make one.