Spots on leaves

I read your diary. I can't find the EC measurement. Your EC might be a bit high for the age of your plant. Next week, you can update your diary by adding the EC measurement. From my experience, I don't add many nutrients to my autoflowering plants since they are a bit more susceptible than photoperiod ones.

This looks almost like a light burn to me. How much light is this plant getting? At 18/6 in veg you should be putting around 300-400 PPFD/PAR on it. If you have a smartphone you can download a PPFD Meter app and test it. On a side note, it appears like you are just watering around the base of the plant. When you water you want to saturate the entire pot. I know it feels like a waste but you want your roots to go out searching for water not just stay in the same spot. If you do not water the outside of the pot then the roots know it’s dry and they won’t go there. Also when watering you will want to make enough to fully saturate the entire pot plus have 10-20% run out the bottom. This helps wash away excess salts that build up over time that would cause issues. I hope this helps.

Looks like you have been getting the leaves wet, as it was exposed to light. Wet leaves, and light generally burns leaves. Vegging doesn't require intense lighting, but it is commonly done.