Hi, My oldest daughter started doing Pulmozyme when she was 9yrs. old, she's now 16. We've always been told that you can move it around from morning to evening but to try and stick with one time frame. But that you can switch it just not morning one day and evening the next. You get the idea. Now, when my daughter started coughing alot at night they recommended she do it in the AM. For a while we did that and it seemed to clear things up as far as not coughing so much at night. Coincidence? I don' t know. We eventually changed it back to nights because that is what she has time for and her coughing didn't come back. Now my other daughter didn't start using Pulmozyme until she was 11, she's 13 now. They started her they say because it was "time" she started not because, in my opinion, she needed it. She's been the healthier one, only one hospitalization (that in my opinion wasn't needed, especially when they said, "oh, she's never been in for IV, it's time she had a cleanout then") Anyhow. She does her's in the evening too. In the summer or on long school breaks we change it to the AM because she gets so pre-occupied with other things in the evening that she gets too tired and then falls asleep while doing her treatment. Changing it during long breaks (spring break, Christmas break, and summer break) they have said is OK. Check with your clinic though and see what they say. This is just what we were told in the begining oh so long ago, and no one (we've been to a few different clinics due to moving around with the USAF) has ever said, "oh, don't be changing it around". I tell them flat out when we've changed from pm to am. When we do change it though I usually have her do it a few hours earlier, like usually she does her treatment at around 8pm, I'll have her do it like at 6pm then the next morning she doesn't do her Pulmo. until like 10 or 11am. She's lazy during breaks anyway so any earlier would be impossible. You may find that you like doing in the evening better. For us, it's more relaxing, no rushing to get things done. Hope this helps, I know I went into more detail than what you were probably looking for, sorry. Liza