Spiking glucose/creating an insulin response it is something that can not be avoided the second you ingest something, it is just the body functions. The point of fasting is to keep those spikes and fluctuations to a minimum instead of the regular roller coaster when we are expected to eat 5 times daily unable to allow the body to rest and digest so please don’t worry you are doing more than most simply by fasting at all. In terms of breaking the fast I usually start with protein and just eat my meal no problem.
At 20 hours you don’t need any special refeed protocol and if you do, it’s probably very specific to you and what you’ll experience.
Personally I like to snack on a small cup of hummus while I prepare my actual meal, that’s usually how I break my fasts.