What is the time frame for arriving in Thailand after receiving a DTV, and how does re-entry work?

The visa itself is valid for 5 years. You could literally enter the date it was issued (as stated on the visa they send you), or enter the same day it expires.

That's the whole point: you are permitted to enter Thailand on that visa within its issue and expiry date. There's no obligation to enter within X timeframe after it was issued etc.

There's been reports of people exiting Thailand at the 180 day point, going to another country whether that be by land or air, and then literally re entering Thailand the next day.

If it were me, I personally would leave it a few days at least. But that's just me being cautious.

Yes, its valid for 5 years so thats the timeline for you. For border run, i did mine on day180, 1minute in cambodia by walking and came back for another 180days

It’s multiple entry come and go as you please. I came in on my DTV and left for Vietnam a week later for business for a few days came back and started all over.

Its a multiple entry visa come and go as you like .

As to how soon you arrive after issued that's up to you.

But remember it starts from the date it is issued not when you first arrive .