Soybean fermentation (cheonggukjang - Korean fermented soybean paste)

Hi, I've just signed up to this forum for asking a question to someone more expert than me about soybean fermentation.
I'm trying to prepare cheonggukjang, I've boiled soybeans, put the straw, kept the tray at about 40° Celsius and waited for 4 days already (the recipe says 3 days maximum). BUT I cannot see yet the typical gelatinous "threads" (or filaments?) such as those of natto. Now I'm wondering: how much longer can I keep it to ferment? Is 5 days too much? I'm afraid to get all the batch rotten (for now no strange smells and no "strange" mold though).
Can you share your experience about long (boiled) soybean fermentation and cheonggukjang production?
Did anyone wait more than 3 days to get the soybeans well fermented?

After fermentation I would pound soybeans with salt and hot chili pepper. I hope to save the batch!
Thank you!

I don't have Cheonggukjang making experience, but this video might help.
Don't try to save the beans after a few days if not fermented properly.

Thanks, I know that video.
Today is the day I'll pound everything or toss everything.
I saw anyway other "preparation" of fermenting soybeans, such as Akhuni or Axon, Kinema from Nepal, other from Manipuri, where they keep soybeans fermenting for 4-5 days. So I think I should give a try to my batch. Thanks

Ok, just as a follow up... I've pounded soybeans and added salt and pepper. No strange mold, neither ugly smell... Just a strong smell (like a mix of baked, smoked soybeans, wet soil, leather, fungus, all together). Hope this is the "right" smell 😅
Now I will keep the jar two-three days at room temperature, and then in the fridge. 🤞🏼

Great.
I'll try to make some this year with new crops.