The Bladestorm change is relatively recent (Feb) information. Really it was discovered completely on accident because we all assumed that Dragon Roar can and should be better Single target damage. The thought that a short Bladestorm would be better overall damage through the course of a fight never entered anyones mind.
You can see the post here.
There is no solution unfortunately, the only thing you can do is try to stay up to date with what Collision and the rest of us post. I promise you will find out as soon as we do! :P
As for the opener:
Using Storm Bolt on the first GCD pushes back Bloodthirst, if you are going to use BzR to skip Bloodthirst and fit a 3rd RB instead, it doesn't matter, but for the follow on CS cycles you will want to use Storm Bolt on the 3rd GCD, or you are doing yourself a disservice.
As I posted and Meteo explained above, using BzR is a rather negligible damage increase. It
will increase your short term damage on the pull, but if you find yourself with a follow on BT and CS that didn't crit, it will be an overall dps loss. The choice is yours of course, I personally find that I like having BzR as back up in case I get unlucky.
For reference, I am completely best in slot and yet I still find myself with back to back non-crits, take it how you will.
I also find it easier to always keep a consistent rotation. Instead of starting with CS SB RB RB RB then changing to CS RB BT SB RB; I always use the second.
Why? Muscle memory. I don't have to think about it, its is automatic, I just do it. Free's me up to watch other things. Obviously this won't apply to everyone but my vote goes for consistency.
Also, keep in mind "I noticed higher burst on opener" is not a very valid metric. Simple things like (un)lucky crits and slight variation of trinket procs can make a lot of difference that is hard to notice. It's why people do not put much stock in target dummy tests anymore. RNG will be RNG.