Auto Blue dream’matic (Fastbuds)

First week of watering with nutes has gone well so far. But I did notice some very light discoloring on the base leaf of “Ricky”. Not sure if it’s anything to worry about or not. (Hard to see in the photo, it’s the blurry faint coloring on the bottom base of leaf) Will continue to monitor it and see how it moves forward. I examined all leaves, above/underneath and found no insects etc. Also looking to spray with neem oil as a preventative soon! When and how should I do this? I have read online that spraying young plants can be risky. Is this true ?