I took it as every time jump went though stardate whateveritwas on it's way to it's final destination. All seven were sent by Burnham, her mother's travels seemingly didn't leave them, otherwise they'd have been investigating that stuff when Spock was a child.
That's a bit problematic: why would only seven of the time jumps leave red stains at
whateveritwas, even though Michael was using the same type of time machine as Gabrielle, and they apparently did thousands of jumps put together? Also, how come two of the stains end up in places Michael wanted to mark (one of those, Terralysium, she marked twice!), but five in places that have no significance to Michael?
How a sign is made is left somewhat open, too. In "Thunder", it seems traveling by the angel suit results in red burps all along the path (perhaps Michael is popping the clutch there or something), yet in "Brother", there was the
whateveritwas sign and then a quick repeat to lure the heroes in, yet also a third angelic appearance, the Michael-to-Michael thing, which didn't involve galactic red glow at all. Sometimes it seems the time-wormhole necessarily glows red, sometimes it does not, and redness is perhaps activated with a push of a button, such as when Michael guides the ship to the future. And then we get to see the timehole up close, in a couple of different settings, and there's nothing red about it. (Also, what is there, the gamma burst and gravitational waves, is NOT associated with the Red Signs by the Admiral who questions the heroes who remained in 2258!)
Whether a Red Sign is worth investigating is a question unto itself, too. The skies were full of them in 2258, but it seems nobody really cared one way or the other, save for Starfleet sending Pike to discreetly investigate. How does one secretly investigate a phenomenon famed for being visible to everybody? Apparently by virtue of nobody caring. Heck, the regular heroes initially saw nothing, and had to be told by Connolly that the skies were full of wonders!
While S2 writing was a mess with a broken back, it's not as if the initial Red Angel story would have been without its conceptual problems, either. But the sum total of all that is that what we have in our hands is a mystery - probably as originally intended. Which is fine and well. I just wonder when the heroes themselves realize that Michael did not make, and could not have made (except perhaps by curiously serendipitous accident), the Seven Signs...
Timo Saloniemi