Looks like he is having a really good initial response -- yay!
When you're first starting, before you have lots of data and know your kitty's responses well, the "no shoot" number is 200 (on a human meter. I think you're using that kind vs. one formulated for pets; e.g., Alpha Track?). We hope for about a 50% drop from the pre-shot (PS) number to the nadir, which is typically around +6. That's just what Riddick did for you today. A well-regulated cat will have pre-shot numbers in the high blues or low yellows and nadirs in the dark greens.
A couple of things might happen now that your testing/shooting. 1) his PS number might actually be higher than the previous one! This is usually because kitty's body responds to what is *for him* a "low" number. Your numbers today were perfectly safe, but they are not what he has been used to, and when that happens, sometimes the cat's body dumps stored sugar into the bloodstream to counteract what it *perceives* to be a low number, resulting in a higher PS. This is called "bouncing." Or 2) the diet change + the insulin support may keep bringing those numbers down, in which case we'll want to reassess your dose. 2 units may be somewhat high to start on (don't fret about it, though! It's what we started on, too, per vet's instructions.), so you just need to be attentive, as you're doing, and post for advice if you get a lower-than-expected pre-shot number.
Also, and this is just as a precaution, since you're stocking up on foods, do pick up a few cans of food with "gravy." This is terrible, awful stuff chock full of carbs, but it is *exactly* what you will want to have handy if Riddick drops too low (i.e., into the lime green range). You'll want to create a little "hypo kit" with the gravy food, some honey/syurp, and maybe some treats like Temptations (also contraband except during emergencies!

), as well as a little cache of extra strips and lancets.
(That's not meant to scare you at all! It's just really good to be prepared always, and esp. when just starting insulin while also changing foods.)