According to plagron's description of Lightmix, "Lightmix is mineral pre-fertilized for one week."
This is similar to using something like pro-mix. It comes with a light charge, then you have to provide 100% of the nutrition going forward. You should treat this like a soilless grow, assuming the fertilizer is 100% plant available. I looked at the data sheet and tried to figure out if biobizz meets that standard, but it is inconclusive. Since it has sugar and other things, seems more geared toward typical soil growing, not soilless. You don't need to feed the biome around roots if the nutrients are already plant-available. It's already beyond that step.
so, it comes down to a preference of style. Either treat it like soilesss, which is what i'd suggest, or treat it like soil... if using soil-focused nutrients, you need to feed the biome as well as the plant.
if you treat it like soilless, simply look up the basics on cocoforcannabis.com -- it really doesn't matter if the inerty medium absorbing water is coco or something else. it changes nothing as far as how it should be treated.
how much and when depends on how you choose to handle this medium. The info on those fertilizer products is lacking, but seems more geared toward soil growing methods.
start slow and ramp up... always easier to add more than it is to take something away that's been overdosed. Based on description of light mix and how long it's been in the pot, it's definitely ready for fertilizer. Up to this point the roots have moved into 'virgin' soil and continued to support itself, but there is not much in there to start. The company says to start fertilizing after 1 week