The written guide is bad. Lead with Bloodletter? It is an off GCD. You use it between abilities while on GCD or you are wasting animation time. Lead with Straight Shot for the crit buff > Bloodletter when GCD is about half. Straight shot's minimum animation will have passed by now and Bloodletter will activate. With Bloodletter used that early its minimum animation will pass before the GCD is finished so you lose no time. I go Windbite next since its per tick DoT is stronger and then I use Venomous Bite. On boss fights I squeeze the self buffs in between GCDs since they themselves are off GCD abilities with a minimum animation.

The basic rotation is a priority system not a set order of attacks for Bard. Heres the priority list I use with Misery's End and Bloodletter left out as it is assumed you use them between GCD's every chance you get.

Straight Shot Buff
Windbite DoT
Venomous Bite DoT
Straight Shot autocrit
Heavy Shot