Double pinkies: when should I do it?

I have about a 2 month old corn snake, and I was wondering when is a good time to feed him two pinkies in one sitting? He just started to learn how to strike at his food (not constricting yet). I heard people usually feed two pinkies versus a fuzzy if the snake isn't big enough yet. I also don't really know if my snake is undersized or normal sized. I got him at a snake expo back in September, and it looks like he's gotten longer since then. (One shedded one time so far since I've had him, not sure how old he was when I got him but he looked at least a few weeks old).

Do you have a kitchen gram scale you could use to weigh him? If not, you can eyeball the size of the prey - it should be about 1 to 1.5 times as wide as his belly. Personally I prefer to skip double pinkies and move up to peach fuzzies once they hit around 15 grams or if a single pinkie isn't leaving a lump anymore. With the mice I buy, two pinkies ends up being larger than a single peach fuzzie anyway.

I don't have a scale, but I also didn't know how inexpensive they are haha. I will get one soon and way him in a couple days. I tried to feed him a live pinky last month, and it was larger than the frozen ones I give him now. He didn't want to eat the live one since it was too big for him.

So once he hits 15 grams, see if he's big enough to move up to a fuzzy? I just want to make sure I'm giving him enough to eat.

Thank you for your help with the other post I've done too haha.