To be honest every one will have a different scale of dosages. I would advice to not go crazy.. I only just got nutes this Is my fifth grow and I only got em to boost my yield and have a deff free plant.... In other words I read my plants and hear what they say lmao I only hear em when stoned. Feed only if there is a need unless you are production person or if you like a boom bastic yield then wait for the big boys lol.. I'm too caring
The second fan is a must but to be honest you said led fixture so the one should be fine I think. You plant looks good at 4 days other one is abit pissed off tho.. Don't be afraid if your plant looks in a bad shape because that's how you will get help.. Good luck and they are good