Ok so about burying your stem when the plant has been growing for a week... first of all when you plant a seed, transplant a plant, or start a clone in soil, you should always fill the pot up JUST BELOW the rim of the container that you're using. By doing that you allow good air flow to the top soil and stem of your plants, GREATLY reducing the risk of mold/fungus and other stale air/moisture control issues. That being said... you'd never have the opportunity to bury your stem, and even if you could possibly bury the stem, you absolutely do not want to do that. Soon as your plant starts to grow and begins developing a root system and what not, it grows differently above soil than it does below soil. So to bury something that was intended for above soil growth, will cause problems, such as rotting of your main stem. And without a main stem, you will no longer have a plant. Do not bury your stem at all.

All that being said, one of the best things you could possibly take away from my advice is... Let the plant do what it is meant to do, and what it wants to do. Even growing indoors, you're not going to be able to beat out nature, or modify the couple years of evolution cannabis has been through. Its a very resiliant plant, so don't fix it until its broke, fix it when its broken, and only then, and when it likes something, be a good parent and give it to your plant in reasonable moderation, or you'll end up with rotten offspring.