A coleção de meteoros observa as mudanças corretamente

• 
  adicionar o campo created_at aos documentos
  
• 
  adicionar novo filtro de documentos ao observador pelo campo created_at
  

groups.insert({
            created_by:Meteor.userId(),
            created_at: new Date(),
            .......
        });

var now = new Date();
groups.find({created_at : {$gt:now}}).observe({
    added: function(document){
        console.log('groups observe added value function');
        console.log(document);
    },
    changed:function(new_document, old_document){
        console.log('groups observe changed value function');
    },
    removed:function(document){
        console.log('groups observe removed value function');
    }
});