Unlike the person you quoted/asked, i'm just a simple "casual" trying to make my way in the universe

, but here's what i did last nite to find mine: Fly into SOL system, solo mode ( or PG ) , drop into Nav Beacon zone and scan, pop back out into SOL supercruise space, fly around while checking panel-1 for any
Unidentified Signal Sources to scan until i find either an
AX Weapons Fire zone to drop into or an
AX Ship Signatures zone to drop into.
Then just wait in those zones, while the AX NPC ships chatter, until eventually onboard computer will announce jarbled "Frame Shift Drive detected" and Thargoids will spawn.
Usually, for me at least, it was only a few 'scouts' at first. But i believe the higher Threat #'s should yield larger/tougher types of Thargoid ships like Interceptors & such. Anyways, the spawns would repeat for a couple cycles, the longer i waited in the zone. ( depending upon zone timer counter and depending upon how fast i destroyed them, since some zones have more green NPC AX helper ships who all fire upon any Thargoid spawns too )
At some point, for whatever reason, i'd stop seeing any
Unidentified Signal Sources appear on radar anymore, no matter how much i'd fly around SOL system. Therefore, i would then hyperspace out to another nearby random system ( 1 or 2 jumps ) and just re-enter SOL system again to rinse/repeat above process.