Yes you should start feeding at around 2 weeks but nothing to worry about right now as long as you start soon.
If you already have a feeding chart you're following just go with it. If you have the bottles only, follow the instructions on the bottle. I suggest you get a feeding chart for the nutrient brand you're using. Most of them have a bunch of "extra" nutrient bottles... You don't need to go and buy every one of them, start with the basics, do your research and buy the ones you think are best.
Good luck with the rest of your grow.