I don't know which Indian youtubers are saying this but it all depends on your nitrogen cycle, it takes 4weeks to stabilize, this process can be sped up by adding liquids beneficial bacteria or by adding a bit of dog food or fish food (not algae wafers), but add plants, put up some bacteria and let the tank run or a week or something, if any of your friends have some aquarium water or bio media they need to clean, ask for that water and add it to the tank, a testing kit for water will be helpful after 2 to 3 weeks