Well, by the end of Perez' run she seemed to have control over it. When she's chatting with Diana's first Generic Cop Friend after escaping from Circe, she's in Cheetah form and seems completely in possession of her faculties. Which makes sense - Circe messed with the transformation process, making it possible without the elaborate ritual and sacrifice, so the transformation itself taking on slightly different attributes follows pretty easily, and she's been able to go furry without bloodlusting relatively consistently since then.
Though even before Circe, she had a fair amount of control. She picked her victims as Minerva, after all (with an eye for staying under the radar, up until Diana), and was able to successfully follow through on those choices once transformed. We don't find out whether she ate the khunds, for example, after they get the lasso for her, but if she'd decided as Minerva that alien cuisine was unwise, I imagine the Cheetah would have just left off with a light evisceration and found dinner elsewhere.