Fertilizer is ubiquitous stuff. There's not tiers in quality except maybe the organic stuff with unknown quantities of nutes in them... that's a matter of trusting the producer can make it with some consistency, but it'll always be a varying amount of nutes in it.
FFOF should be for for 6-8 weeks. If you added some perlite or similar, which you should definitely do, the nutes that come baked in will take a shorter time to be used up.
That's all about trial and error and finding a ramp up of fertilizer that avoids any deficiencies as the nutes in the soil are used up. I'd suggest being a bit slow the first run. Take note of when you start to see some symptoms, then slowly ramp up fertilizer. The next cycle, divise a plant to pre-empt those symtpoms. Adjust your ramp up based on what you see this time, rinse and repeat until you find that goldielocks zone and nearly all plants react well to it.
Plants in reality aren't that picky, but a poor formula will rub more plants the wrong way than a good formula.
I've even used hydro nutes in FFOF, lol... far better than the first cycle where i used FFOF trio. Those are trash and their feeding schedule is trash too. I re-used my ffof 3 times before i threw it out. it was moer like a soilless substrate after the first use. I did add some perlite to make it ~50% drainage amendment including what cam in the FFOF to start. Definitely top off heavy soils with more perlite or similar. 50/50 is good for soil. only need 33% in a coco based "soil" substrate because it holds less water per volume. That doesn't make it better, just different.
