When DS has a cough we're instructed to call his doctor and a determination is made as to whether or not to proceed with ABX. Usually we do. We're also told to "beat that cough/wheeze" out of him. So we increase CPT/vest from 3x to 4 times a day. Sometimes increasing the amount of time we beat him. And sometimes we'd give him an extra mini-beating while just holding him without his bronchiodialators (nebbed albuterol and atrovent)
When he was a baby, I'd use the saline and bulb syringe. Teeny tiny babies have a difficult time getting rid of that mucus from their noses. I'd also get the bathroom all steamy and give him a bath in the morning and one in the evening to help get things moving.
When DS was ellie's age he got a horrible cough, which the local CF doctor told me it was normal "It's what they (cfers) do, they cough". This went on for several weeks, the kid would cough so hard he'd throw up his formula. Went for a clinic visit in the city and it turned out he had bronchitis. They did a culture and he had enterbactor choacle (sp). Within a couple of days of abx he was fine, but we'd messed around with it for weeks.