To put your mind at ease. mix your sugar and water solution up that you are going to put your grains in.
Before you put your grains in, have a small teaspoon of the sugar water mix just so you can get an idea of how it tastes.
Try it again after 24 hours and then again after 48.
You should notice a pretty large difference in sweetness. If you don’t, you have bad grains but that almost never happens. Takes a lot to kill them.