Hi,
from my experience trying to specify the order for bundles to start is very problematic.
The only time I attempted to do this was when one bundle was dependent on another bundle performing an action/updating content. Unfortunately the client did not have time to rewrite everything, so I added checks in bundle B to see if Bundle A had completed all it's activities, before allowing bundle B to start.
Another approach, if there are no dependencies between the bundles, would be to kick off a job for the bundle that takes a long time to start, this job would then run in a separate thread and run the initialization of the services, in this way the other bundles/service would be free to start quicker.
Regards,
Opkar