That should be good as far as the nutrients are concerned. I do not leave my plants in darkness before harvest, I have tried it and it didn't seem to matter. That being said, I know that many do kill the lighting before harvest, and swear by the tactic. Again, this boils down to what you are comfortable with, because you are much more likely to succeed and be personnaly happy with the grow results if you are comfortable with how the grow was handled.
Like you, I was nervous as shit through the first couple grows, but familiarity breeds contempt as the saying goes or in our case familiarity breeds comfort. Finish this grow, wait 3 weeks and then smoke a "J" and reread your notes and the grow log here. Learn from where you have been and the actions you took during this grow to properly plan for the next grow. Decide what worked and change what didn't. Always keep learning and refining your approach, as humans our mind is programmed to learn from birth, and when you stop learning and thinking its probably time to go on.
You've done fine so far, and you will do better next time.