ADHD hack that helps with my time blindness: if I haven't taken my meds and I really need to focus on something, like homework, I'll set a timer on my phone for 2-5 minutes (I give myself less time if I'm more distracted). If my mind wanders without me realizing, the alarm going off will kinda help bring me back to the present.
I just keep resetting it as I go along. I also feel a little boost of "accomplishment" every time I manage to get through the timer without losing focus, and those little boosts can really help on bad days.
My "time blindness" can be really bad - I'll just lose massive chunks of time without realizing until it's too late - so this helps with that specifically. It isn't foolproof, I know, and some days even this can't keep me on track the way I want to be. But it helps, some days, when I'm really struggling to be aware of the time. Hopefully it helps someone else:)