My docs would likely have me wait. They too would go by how much it was and how I feel. I am also always told to go to the ER (gulp) if I feel worse before an appointment date.
I'm rarely seen the day I call in, even when I feel really sick. So, I can sympathize with you there. I THINK if I'd call in with your symptoms they'd tell me to wait until Monday and go to ER if I cough up more than XYZ, etc.
Its really frustrating though. I would think with CF they'd make an exception. However, most everything I've ever called in with (blood, pain, SOB, tightness, etc.) its always met with "oh that's really common for CF".... they almost always want me to "watch it" for a few days until I can get in. Again, very frustrating.
I hope you feel better!