Last time I was at the doctor's office they gave me a sheet on this. It looks like it came from an Australian clinical trial for Hypertonic Saline. I'll quote the section about order of meds. Also it was suggested that airway clearance could be combined with the first two meds to save time.
"A brochodilator was used (fast-acting agent via inhaler or nebulizer) 15-60 minutes before the hypertonic nebulized therapy.
Aerosol therapies were administered in the following order:
Bronchodilator (Albuterol, Xopenex)
Hypertonic saline
Airway clearance (CPT, Vest, Flutter)
DNase (Pulmozyme)
Corticosteriods (Advair, Pulmicort, Flovent)
Antibiotics (TOBI, Colistin)"