Northern lights auto. First time grow

Got a new light: Mars Hydro 300 and am very happy so far. realised that my timer wasnt set correctly so it has been getting 24h when i wanted to give 20, i corrected this now. Some of the leaves have a little yellowing to them that i believe is because of mild nute burn from the soil that is prefertilised. I have read that it is fine and that the plant will grow into it, please let me know if you disagree. All in all a good week with a lot of learning and very fast growth. the first pictures are before I got the new light and i believe the plant wasnt getting enough. last pictures are from today, day 14, and the affected leaves are the ones that came first and grew under the 54w light. Please let me know what you think about the yellowing.