In the vast majority of flights I have been on they commence loading cargo before passengers and finish during or after. I have the sliders set to give a realistic feel to all the components offered by GSX. I suggest you take a look at them.
As explained on the GSX manual, and as discussed many times already on this forum too, everything that involves timing in GSX is SCALED DOWN in comparison with reality.
You won't see 300 bags being loaded on a 300 passengers airplane, because nobody would want to see 30 minutes of the same animation, and vehicles also have more moving limitations on the apron compared to their real life counterparts, because there's no intelligent driver and the program doesn't have any notion of the actual scenery obstacles, which means the baggage trains are also shorter than might be in reality ( to lessen the chance of collisions with something else ) , which is another reason why everything IS proportional to the estimated number of passengers, but scaled down with reality.
The passengers boarding time doesn't have these limitations, because it's just a waiting time with an audio effect looped, which is why we ARE allowing you to make it as long as you please, mostly because you might be using that time to do your cockpit preparations, but if you make it realistic, it will always end after the baggage loading which, as I've said, has very sound reasons why it can't be timed 1:1 with reality.
