So many of us use an opener similar to yours except we do DK instead of Twin Snakes. After you complete your PB combo then start with DK/BS (doesn't matter, both are the same since no form bonus), and then Twin Snakes. I ToD after I Twin Snakes that way it's fully buffed, and then you'll complete that combo with Demo. Then it's just business as usual.
So PB -> Demo -> BfB -> Snap -> IR -> Snap -> Steel Peak -> DK -> Howling Fist -> Snap -> DK/BS (whatever you feel like since it's non-form) -> Twin Snakes -> ToD -> Demo -> back to business. That is what I use as well as many others. The DK debuff will net you just slightly more damage than the Twin Snakes buff. This is the reason we use it first. In the end the opener is just an opener, and as long as you get GL3 fast the order isn't going to amount to very much of a difference. I just wanted to make sure everyone knows that DK can be applied in PB.
Please note that as you start going through you next combo (BS->True Strike) you will lose the DK debuff for 2 moves. The math apparently works out so that doing it in that order still nets slightly more than not letting it drop for those two attacks. I didn't bother doing the math myself since after a lot of testing the difference is minuscule either way, and the person providing the combo as well as doing the math is highly reliable and tests things along with doing the math. We're talking about only the first 20 seconds here anyway after that DK/Twin Snakes will always be up so I wouldn't stress too much on the opener as long as you are getting GL3 as quickly as you can, and getting your CD cycle started.
