Hey there Mark Davidson,
Nothing wrong with getting a little excited, I wouldn't say that means you got the cart before the horse.
You have plenty of options, and some good ones have already been presented here. One that hasn't, but is certainly traditional, would be nesting and green leaves.
You've probably heard about hornet's nesting, but regular old wasp's nests that you see hanging off the side of your house works just as well.
Or you can pull a handfull of green leaves off a nearby bush; as long as you make a tight wad, it'll keep the shot from rolling out. You might just add a little of this on top of what you're already using as a stop-gap measure.
Now, I do recommend miking your bore and finding out what you really need. Bore sizes vary from manufacturer to manufacturer, and very often vary within the manufacturer too, so you really do have to find out what you have. But you definitely don't have to stop shooting until you get it all figured out and receive the correct stuff.
Congratulations on your new gun. I hope you have lots of fun with it like I do mine.
Spot