New set up questions (beginner)

So I'm not 100% new to fishkeeping/tannins but I am a beginner when it comes to RO/distilled water/blackwater set ups. I'm planning on setting up a new, straight-out-of-the-box 30-gallon tank this week.

My tap water is hard: ~7.8-8.0 PH, 150+ TDS, 5-8 KH, 10-12 GH ... I think. So for my current neocaridina shrimp tank, I was able to cut the initial fill up with grocery store distilled water, which I also use for top offs. My goal for my new tank is a blackwater tank with something like 5-6 PH, 0-2 KH.

I'm still working out exactly how to achieve this. My internet research is telling me to fill the entire 30 gallons with distilled water, slowly add boiled botanicals and live plants, wait until it reaches stability, and then stock with fish. This doesn't seem right though, since it seems to "pure" for livestock, but I also fear remineralizing will stall the PH drop.

Can anyone give me the proper steps for this? When do I remineralize/stabilize? How do I assure the tank is safe, especially if livestock comes from ph 7.0 water? Should I drip acclimate?

I've also been trying to figure out my future water change routine. This is my plan based on internet research: fill a 5-gallon bucket distilled water and a to-be-determined set amount of botanicals, let it sit for a week, remineralize, and use that for water changes. Is this correct?

TL;DR I don't know what I am doing. Can someone send me guidance?