I'm a big fan of Fluoride rinses (ie. ACT). I have been using one every night for the past 30 years and recommend them to most of my patients for raising resistance to tooth decay and helping prevent or lessen tooth sensitivity. Once a day is fine, but remember to avoid rinsing with water after using the Fl rinse for maximum benefit. It will continue to "soak in" for the next 30 mins. If you want to rinse in the morning, I would recommend an anti-plaque rinse such as Listerine or Crest Pro Health to decrease plaque bacteria.
Hope that helps and keep up the great work!
Fluoride rinses will help and can be used twice a day. Talk with your general dentist about it. It depends what the fluoride rinse is as well. If its just crest or listerine then you should be fine. There are prescription fluoride rinses you can get from your general dentist which are stronger and you have to be careful how much fluoride you ingest. Otherwise, over the counter, you should be fine.
You can use that after each meal/snack. Cavities is a very preventable disease and plaque is the root cause of it. If there is no plaque on your teeth there should be no decay.