The 4-8 weeks thing is just a myth. Read up on this please: https://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/It’s a 230litre tank
Ok, I have been told that guppies should only be added once the tank has matured at least 4-8 weeks. I also am interested in neon tetras.
Its a nice looking tank.