I have a TON of cast iron. It’s all I cook with. This little beauty is a 6.5 inch that a friend gave me so it fits just fine in a toaster oven.
Even though your pan came preseasoned I like to add 3-4 more seasonings before use. You can just start cooking with lots of fat, and that should be fine, but extra layers don’t hurt. I heat the pan to 300, then coat in fat of choice, mine is currently lard. Let cook for 15 minutes, take a dry paper towel (I use the blue shop towels because they have less lint) and wipe out excess oil. Raise temp to 350 for 15 minutes, wipe excess oil, raise temp to 400 for 15 minutes, wipe excess oil, then raise temp to 450 and bake for an hour. Let cool, rinse and repeat 2-3 more times.
Or, just cook a lot of bacon and fatty steaks.