Grey leaf tips

Your plant isn't old enough to see a visible Mg-deficiency. It may or may not be present but it doesn't show a symptom for 30+ days after the defecit of Mg begins. Mg-def would have interveinal chlorosis and spots - starting lower on the plant (mobile). This is not seen. Get a left symptom chart. Don't go by word of mouth for symptoms. Once you reference it enough as you learn to refine your fertilization methods, you memorize it by accident. Hard to tell for certain, but before looking into nutes, i'd ask about watering habits. If you don't allow the top 1" to dry (a more superficial layer, if coco) before repeating, then you are possibly causing the dead ends with overwatering.. this would more often be interveinal to start, but .. possible still. Looks a bit mottled on the one leaf and that's far too early for age of leaf points toward overwatering too. Even so, looks like a N-deficiency. I see the coty is a bit faded at tip. LEss likely a s-deficiency. I looked at diary.. light is a potential issue too. i see the tacoing reduced after you drew it back. You might want to just see how the light adjustment continues to play out as well as fixing any watering habits. As long as the plant doesn'tshow continued progression* - soil is always some guessing due to current state of nutrients in the soil.. supplement more each week but starts of slow with unique needs. Take notes even if it was less than ideal results. if you use the same soil next time, it'll be a very similar 'ramp up' as before. do better each time until you have a very healthy plant seed to harvest.