Nute burn or Nute Defficiancy?

Hey everyone, I am new to growing and just thought I would give it a shot (growing for self of course!). I created a grow box out of a Rubbermaid container for starters. It has 6 CFL bulbs each giving off 1700 lumen s per. I had them on a 24 hour light cycle for the first 2 weeks and now have switched them to a 18/6 cycle.I'm currently on my third week of vegging and it seems to me that they are a little small for their age. I'm not for sure though. Also, some of the plants seem to have yellow colored leaves and a little charring on one of them. I'm thinking Nut. burn, but once again I'm not sure. The soil I bought did already have some nutrients in it which is why I haven't gave them any yet. If anyone can help me find a cure or give me any advice for growing I would greatly appreciate it.

Pictures are below!

I'm also beginning to believe that it may be due to nutrient defficancy....I was thinking about getting some Flora Nova Grow tomorrow...what do you think is the right direction to go?

What kind of soil are you using now?
Some ptting soils are too nitrogen rich and can burn young seedlings.

Should seedlings this size even be getting nutes?

You arent using a time release soil by any chance are you? Soils that are "time released" or anything like that release nutrients every time you water so you have to be really careful with them. Oh and some pearlite would be good too for soil drainage