Don't be surprised by some swings, especially this early in the diagnosis. Heck, it was weeks before we even saw numbers in the 100s. You're still searching for the best dose, and Jack is still adjusting to getting what his body needs. As his body adjusts to getting regular amounts of insulin, the numbers will become more consistent. You'll still likely see a low point somewhere in the cycle.
Others here will have more detailed answers, but seems to me that you're off to a great start!