it's going to stretch quite a bit if it's only source of light is daylight. With mine it took about a week and a half until I started seeing nodes. You'll probably have to stake it to keep it upright too, because a lot of the plant's energy is being put towards growing upward (to find light) rather than outward. The only real way to stop it from stretching is to give it some artificial light.

As far as when to start using nutes, you should probably hold off for a while until you start to see some side branches, and then only use nutes at a very weak strength, like 1/8 normal dose.

I hope that helps.