Starting to flower a 4 foot tall mama!

Hey everybody, so I've been using this mama plant of Rocklock for a while now to get some clones and start myself off, and she did me well! I'll admit, we had our problems from time to time, but lately all has been great and she grew faster than I could use her clones. So I decided I'm going in to flowering mode! I'm using a hydro DWC system and botanicare nutes. I've got a 400w HPS on top and giving some light down below are three 100w equiv. CFL's. I just started the 12/12 cycle today and added more water to the bucket. I'm thinking that in about a week or two I'll go full on flower mode and bust out the bloom. I've been using botanicare nutes with Stinkbud's Poop Soup recipe, which has turned out well. depending on how much water gets soaked up in the next few days, I'll decide if I should mix in some PBP Bloom to give her some more nutes. hopefully this turns out awesome and she yields huge. I'm just writing on here for anybody that feels like giving me some tips or ideas on things I should be doing. The only real question I had was when to start using CO2? and I don't have a tank set up for this, I'll just be misting on carbonated water. Has anybody done this before? Well there's a pic from the day one below, and I'll keep posting more as this goes along, so feel free to give me any input if you have any! Otherwise wish me luck! Hopefully I can handle the size, I think I need to steak her soon so she doesn't fall over from being top heavy!