Hey mandy. Good idea on just the water. Not saying that the Nitrazyme wouldn't work or help but it's better to KISS(Keep it simple stupid) for starters. I have been learning this too, some of it the hard way. My main advice. PH PH PH PH PH PH PH PH PH PH PH PH PH. Short of making sure your plant isn't on fire or under water you HAVE to make sure your ph is on always at all times constantly no matter what. And with auto's you don't have a lot of time to fix problems that won't hurt their yield most likely because of their short lifespan overall. Almost all new grower's problems start with ph problems. That is the very first question most people here will ask you when you have problems. Sooooooo. Anywho...
When you say your water is always at 7 what does that mean exactly?
You have the biobizz flowering nutes. You Can start on those when it starts budding, but what most everyone does and recommend here is start those a good bit later. You will be able to get more out of your plant if you wait on and the flowering nutes. When you start those your girls will stop vertical growth and all vegetative growth and start working and focusing energy on making flowers. Which is ok if you're in a hurry it will work, but it's best to give her veg nutes until the buds form more. Now when exactly I don't know, but someone will chime in here shortly. Hope this helped.