Yes, you can freeze homemade stromboli. I like to freeze them before they get baked so that I can cook them later. When I am ready to bake them, I just let them thaw out and then cook according to the instructions. They come out great every time. You can also freeze the stromboli after it has been baked.  Just let it cool and then place it in a freezer-safe bag or container. When you are ready to eat it, just reheat it in the oven until warmed through. Of course, I much prefer to slice cooked stromboli before storing them in the freezer so you can reheat a slice at a time easily.