If you are seeking a total organic soil grow, I'd look at a 4-4-4 all purpose or 4-8-4 flowering fertilizer. In my first year of organic growing, I've learned this. You can add a little more, but you can't take away without a replant. Since I created my own super-soil and only use water from seed to harvest, I'm probably not the most versed in this. I'd say if I were at your position with my knowledge, I'd wait until about week 3 to add nutes as the Fox Farm has a small bit to help it get started and you don't want to burn it in it's young state.
At about 3 - 4 weeks, I'd add a 4-4-4 mixture (amounts based on your pot size and the brand you choose) to the top and water it in. Check out Mr. Canucks Grow on Youtube. Amazing example of organic grows. Look into Super-Soil. It is a bit to get started, but once you have a decent batch, you can grow with minimal effort.
I just harvested 2 plants and am looking at 8oz between the 2 of them watering only from seed to harvest using my own supersoil batch. The recipe for it is in my profile and one or 2 of my current grows.