Hi,
1.You need to preload the model that is larger first(the lighter one will be ready just in time).
2. put a movie clip in the same color as the background at frame 1 only one layer above the model.
when the movie finishes loading the larger model ,it goes to frame 2 in which the movie clip is gone,
therefore it seems like the 2 models where preloaded together .
Do you think thats air you are breathing now?