You can test by trying to turn the eyelet with respect to the fabric. An eyelet is one piece where one side is formed/flared to crimp. A grommet has two pieces one swages into the other. Now you can put in your grommet or eyelet. It should only take a couple of seconds exposure to the heat. The fibers around the hole will fuse nicely since they are most certainly nylon. (I recommend practice before punching up your BCD.) If everything went right, you will have a clean cut that is exactly the right size. Punch your hole by making one good hit on the end of your punch with a hammer. Make sure nothing is under it that can get damaged. Put a piece of wood inside the pocket to absorb the blow of the punch. Make triple sure it is exactly where you want it because you cannot undo anything from here on. Mark where you want you hole with a silver sharpie. You can make one that will suffice a few uses by buying some kind of tube the right diameter and sharpen one end. You can get a set of these at Harbor Freight or similar for really cheap. They are not the cheapest, but they have most anything. A good source for almost anything is McMaster Kerr. The next best is aluminum, then zinc plated brass. The best is stainless, but they require a special press. I found some in Germany in the Home Depot type store but they can be found elsewhere and on line. I recommend finding the best grommets (another name to search under eyelets) the size you want. I would not use the methods described nor the chintzy cheap grommets in the picture. I have done exactly what you are trying to do.

Stainless steel grommets home depot