Animating group visibility

First post to the forum and Im pretty green on blender so go easy on me :smiley: . I have created a model that contains about 20 objects (bolts etc). I want this model to appear at a certain point in the animation. Seeing as I have version 2.65 I cant animate the layer visibility so I am trying to animate the visibility from the outliner. It works great for a single object but is there a way to set the visibility keyframe for all objects at once or do I really need to set the visibility for each object. I have tried to group the objects and animate the group visibility but there is no option to set the keyframe for the group. Is there a different approach I should be looking at?

Are using Cycles or Blender Internal Renderer? Do they all use the same matterial?

In Cycles you want a Mix Shader with the material you currently are using plus a Transparency shader… then you can animate the Mix factor from 0.0 to 1.0 from the all Transparent shader to the “whatever you have now” shader material

if in Blender Internal… pretty much the same Idea use Transparent on your matterial settings and animate the Alpha channel… from 0.0 to 1.0…