Fisixanswered grow question 2y ago Hello,
your soil should already be pre-fertilized. If not, you can start fertilizing lightly. A seed can usually manage without nutrients for up to 2 weeks. So when you need to fertilize depends on the soil you bought. But I think you can start lightly right away. Just remember that fixing a deficiency is easier than getting rid of an overdose.
With the LST, you need to wait a bit. The root stem still needs to grow, and once it has 2-3 more branches, you should be able to start. If something breaks or bends, get some tape (most things can always be saved). LST can also be something like a fan that creates a light breeze, shaking the plant, or anything that doesn't really harm the plant.
Hope that helps.