Glaive Toss has an extremely high chance to proc trinkets, a lot of that having to do from the fact that it is 2 projectiles. That is why I use the first glaive toss right away, to try to get trinket procs going before the rest of cooldowns.
As for keeping that first serpent sting up, I wait until the readiness double kill command, then depending on how far the target is from me I either glaive toss as well or immediately get 1 cobra shot off. Then glaive toss, then another cobra shot, dire beast, then use the second bestial wrath. Also refresh rapid fire a few seconds later. I guess you could consider all of these "small improvements" but DPS is all about min/maxing, why not do what's best?
GT doesn't 'have an extremely high chance' to proc trinkets, it just hits twice. I don't think fishing for procs with GT will show a DPS increase. Trinkets often don't proc until 15+ seconds into the fight, so I don't think it's reliable enough to be losing out on consistent damage. Also not sure about delaying the 2nd BW more than a GCD or two because if you do you're losing your pre-pot during or before the 2nd BW which is pretty significant.
Keeping SrS up is definitely an increase and only requires 1-2 CoS, which you can cast during RF.
I dont think you realize how how important trinket procs are when it comes to using cooldowns. Trinket procs can make the difference between a 200k and 300k opening burst. I know in a lot of cases it is very beneficial to delay cooldowns for trinkets that are about to come off of ICD. I dont know exactly how much raiding you do, but I know all the top hunters would agree that it is better to use cooldowns like dire beast and stampede before bestial wrath in order to save those globals during the actual cooldown. Additionally, using dire beast -> bestial wrath instead of the other way around sets you up for the rest of the fight for those cooldowns to lineup correctly, rather than using dire beast during every single bestial wrath in the fight instead.
Back to the trinket proc question, I doubt an extra 10% damage to that one glaive toss amounts to the chance at increasing your burst during cooldowns by many, many thousands. Also, that extra glaive toss is a very small % of your total damage. Considering the fact that your pet does almost half of your total damage, and glaive toss only does a small percent of the already ~half damage that you yourself do (without your pet), that is very small indeed. A trinket proc however would affect both you and your pet, multiplied by the 10% for yourself and 20% for your pet during bestial wrath.