glad you came to the forum; hope to see and hear lots about this little guy's progress.

And kudos for cultivating a live of herps in your son; more kids need that

My advice for you would be to get a thermostst ASAP. 105 at the glass is pretty dang hot, and if your snake decides to nestle into the substrate you could end up with some burns. Hydrofarm is the cheap solution; Herpstat is the pricier one, but more reliable in the long run.

Also, make sure the pinkie is thawed AND up to room temp at least before putting it in the tank; if its too cold you can have problems should the snake eat it before it's warmed up enough.

Size wise, you want a prey item that is about as thick as the thickest part of the snake's body; this translates to 10-15% of their body weight. Once you get a scale to weigh him it'll be easy to find the proper size.