What our doctor told us what that enzymes can last up to four hours. You don't want to give too many in a day--they had told me the max. Our nutritionist though said to re-enzyme if over an hour. Honestly, if it is only an hour I would not b/c you don't want to hit the "maximum" amount, which can be dangerous. I would call and ask your clinic what they want you to do--NEVER hesitate to call, especially early on--they fully expect it. And also ask what is the maximum they want him to have in a 24 hour period b/c at this age they eat so often. . .
Another thing I wanted to share as an idea given what you said about getting a house of 9 clean: I just didn't and don't have time to have a dust-free, clean house. So we basically have "clean" rooms for ds and then assume everything else is dirty and he doesn't "roam" those areas and we wash hands etc. before feeding him and doing treatments if we are in those other areas. It has worked for us b/c I don't worry if one bathroom is "toxic," etc. and can be stress free knowing the other areas are fine.
Re the research: So with d508f the protein doesn't work right in a couple of ways. There is a company called Vertex which has a drug called VX-809 in trials. They just finished Phase 2 and are moving to Phase 3 with Vx-809 and Kalydeco (which is already FDA approed). The results are very good for helping fix the functioning of the CFTR defct. It isn't a perfect "fix" and it isn't a cure, but it is a HUGE advancement and is likely to change everything! It will likely be 3 years before it is to market if all goes well, BUT your grandson is so young that he'll be getting it before hopefully any possible lung issues. You might want to join that facebook page I mentioned. There's a mom whose 4 year old just started Kalydeco and they did an MRI and it showed his lungs are PERFECT--no damage--and the drug is working so well that he is no longer doing many of the treatments, etc. And there is another drug called VX661 which is suppose to be even better which is about 1 year behind. And many other drugs in the works--I truly think these will be ready and will fix the defect before your grandson hits 1st grade!
Finally, I wanted to ask re the breathing treatments--you said for now it is as needed. Were they going to have you start those and chest percussions after your next appointment? If not, please push on this because it is important for 2x a day breathing treatments and percussions as part of the standard of treatment.
Prayers and hugs