I just work my Focus fire into my macro. Sometimes I proc it with 1 charge sometimes 3-4x. Either way it always gets consumed and used.
That pet cleave can be difficult to keep up 100%, but I was running something along the lines of
#showtooltip
/castsequence Multi,multi,steady,steady,multi,multi,steady,stead y
/castrandom !killshot

Not perfect syntax but it got the job done for my needs.