2-300 ppm sounds about right for a small seedling..
dose that for a week or 2...depending on how fast its growing, right now you wont see alot of growth as its focusing on root production, the bigger the container the longer it takes to grow a decent root system think of it like moving into a new house, you wouldnt buy a new living room set without first seeing how much space you will have. you wouldnt have 3 kids knowing you only have 2 bedrooms.
anyways, once the roots develop and the plant starts growing..it will grow fast, especially if you have good lighting and enviormental conditions..a canabis plant can grow 1 ft a week if givin the right conditions. (they are technically a "weed")
once you start seeing good vertical growth you can increase the ppm by 100 each week untill your at around 1200ppm (generally 1200 is the average, some plants like more some like less. learn to read your plant...uniform yellowing and new light growth means hungry, blotchy yellowing and necrotic spots usually means too much) as long as you keep your PH in the range its supposed to be and feeding a complete formula with micro nutrients (minerals like iron, magnesium, calcium, boron...ect ect there are hundreds of micronutrients that plants need but only in small amounts) then the only issues you should see in a plant is toxicity or deficiency...or bug related.
what i like to do and others may agree or disagree but it works well for me.
when you flip to 12/12 i continue feeding veg nutes for at least 1 week of 12/12, then the second week i feed 1/2 & 1/2 veg/bloom then the third week i go 3/4 & 1/4 bloom/veg begining of week 4 (not flower..after flip) you should be feeding 100% bloom, stretch should be done and you should have small clusters of pistils all over the bud nodes...this is when I start my week 1 of flower. the first 3 weeks after flip is a transitional phase where the plant is stretching and begining to store hormones for the change into reproductive cycle.
flowering nutrients: I have had good results from a solution of around 1400-1600 ppm, but again not all plants are the same and i have not grown in cocoa before. flowering nutrients do not contain as high concentration of nitrogen which is the primary chemical that will burn plants so you can use a slightly higher ppm with a bloom food.
i also like to use superthrive @ 1tblspoon per 5 gallon bucket. (so about 1/2 tsp per gal, maybe even less...dont need alot) it seems to keep my plants looking vibrant and healthy.
hope my ranting helps..if its info not needed sorry for the long response. good luck m8