This might not be the case for everyone who has lupus, but butterfly rash is always the first sign of a flare up in my case. I don't get the rash at any other time.
Exhaustion and sunlight are the main triggers for my lupus breakouts. As much as I try to protect myself and prevent it, it happens and I always know that it's coming when I see a rash forming on my cheeks and nose.
All I can do is stay out of light, relax and wait for it to go away. If it gets really bad, my doctor prescribes a cortisone or steroid cream.