I've always found it easier not to use too large of a container from the very start, and instead changed the size of the pots (and the amendments being used in the soil) when it was time to transplant. I see that you may not have that option, which makes it difficult to determine exactly what you'll need to add to the soil from start to finish.

The earliest seedling mixes don't need hardly any nutrients aside from what's already premixed in the soil, and if I remember correctly, Black Gold is pretty rich by itself. For my second transplant - when the plants are in the rapid stages of growth - I like to add blood meal and worm castings to the soil mix, which provides plenty of Nitrogen, but might mess with the pH of the soil. (Though, if you're coming from a hydro background, this shouldn't be much of a problem for you to correct.) And, finally, for the last transplant, I switch from blood meal to pulverized bone meal, adding some worm castings, but less than I used in the second transplant. I also periodically water using a high-Phosphorus bat guano and molasses throughout flowering. Again, being careful to pay attention to pH... which should determine whether or not you use any dolomite lime, and if so, how much.

As for perlite, I've always preferred to use 1 part perlite to 3 parts soil. Some people might consider this excessive, and you will probably find yourself watering more often, but the roots seem to love it.

Have fun getting your hards dirty! :jointsmile: