I owe an update on the resolution.
If Prime is at 7:00 AM, that's fine. The half-hour, then, should start at 6:30 AM, obviously. Then it's just a matter for dialing in on "how long" it takes to pray Matins & Lauds. I've clocked that at about 60 minutes, or 5:30 AM. Which means this morning as I type this, I'm already late, as you'll see at the bottom.
I like the 4:30 AM wake up and the 5:20 AM fast. I was in the kitchen this morning, dressed and ready for coffee at 5:00 AM. Very good, I'd say.
Also, in case you're wondering if yesterday I wrote any thank you notes—even a single one—the answer is yes.
And lastly, if you're also wondering whether the time indicated below corresponds to the time I closed my laptop, got up out of my seat and left to open the Church (or hop in the shower—if it's a Saturday) the answer is yes.