First time growing!

So this is my first time growing and I started the flowering process today. Does anyone have tips for nutrients and what I should watch for. Plus differences between early flowering and late and time periods. Attached is a picture of the 2 I have started. Full one was a clone and the tall one I started myself from a random seed. I am only flowering the clone right now as the tall plant is too young still.

What do you mean you started the flower process ?

I started doing strictly 12 dark and 12 light and changed the nutrient mixture.