Dear No Rocket Scientist,
Even a true rocket scientist couldn't get it immediately. It takes some time.
Ideally: If you have a good bg, say 100, and you know your basals are good (you've done basal testing at all times of day/night), you should be able to dose for carbs eaten, and within a couple hours (or 3) be back to your starting bg of 100. If the 1:16 isn't right, you should either be too high, or too low 2 or 3 hours after eating (the 2-3 hours is a guess based on different carbs being slower/faster acting).
It takes a measured approach, kind of like basal testing, IMO.
