To be honest I observed this behaviour on all Sailfish versions I had, beginning with 3.2 - and I consider it absolutely understandable that it takes it time to start the container.
The start time is fine. The problem is that the behavior is misleading and one might think that the container is not coming up… What is happening sometimes as well…
shouldn’t be too hard to increase the timeout or have a special notification if the container just started
I see this most of the time too (for those few cases i have had AppSupport turned off, that is).
If the app timeout was another 50% or so it would have worked robustly for me.