On another note, #2 of "Batman and The Signal" made mention that Duke's been training under for a year now. That's definitely some interesting and relevant information.
For my part, it definitely doesn't feel like it's been a year. Even when trying to look at things from an in-universe perspective, the out-of-universe reality that Duke has had so few stories together that showcase and feature him under Bruce's tutelage, i.e., them out on adventures and cases and stuff, it really feels like he's only still just started. Still, thinking on it, given the opportunity, I'd love for Tony Patrick to do some stories of Bruce and Duke pre-Signal/pre-Dark Days to flesh out that time period.
Anyway, since it's been mentioned that, according to Detective Aisi's observation, Duke's been with Batman for at least a year, I wonder if that means Duke is 17 now? Would help if his age was directly brought up, but we'd need a good reason to do so. It would have also been nice to have had a little birthday celebration for Duke if it is the case that he's 17 now, and maybe if the character had something akin to consistent page-time and presence in the book he was supposed to be in, maybe we would have had one.