Correct I often don’t have any connectivity at the launch point. I think you are right that the initialization time corresponds to the size of the mission. Short flights always spool up quicker.
I’ve also seen elsewhere comments about longer flight plans appearing to be truncated on the initial launch and reappear after flying part and swapping batteries. This has always been my experience ever since the “initializing” feature was added. I always figured that was just representing the limit of how much data was sent to the drone. It was always more than enough flight plan for any one battery. In my opinion, if my interpretations are correct, that is a good safety and efficiency feature that allows the drone to operate autonomously even if signal is lost, which happens to me occasionally in forested hill country.