I'd say your 14-16 weeks out for sure. take the first 4 weeks and structure your diet (log calories, rid yourself of processed sugars, cut sodium in half, start eating "clean") You have to have a starting point of where your carbs are on average, then drop them accordinly until you hit a sweet spot....Then start the 12 weeks of real pre-comp dieting. Making sure your protein/carb/fat ratio is in tact. It takes time.
I start 14 weeks out everytime. I'll leave the protein fat ratio out. Thats the easy stuff. CARBS is what can make or break you essentially.
Starting carbs are 400-450g complex. Halfway point they are at 225-250. Final 2 weeks 150g down to possibly 90g depending if I see muscle wasting occuring. I always carb load on sunday to have a energetic week. Protein/fats are consistant thoughout with slight variations depending on what the mirrior tells me. If this is your first comp. Than stick to the basics, don't get to hung up on carb/sodium cyclying and by no means attempt the ketogenic diet ( close to 0 carbs), I did this my first competition and felt like shit, lost alot of muscle and felt very weak. I went from 235lbs to 185lbs in 12 weeks my first competition, and it was brutal. After your first comp, which I see you doing very good, it will set you up for a better 2nd and 3rd. Take your pride out of the equation for this one. You have to realize your competing against guys who have done this for years. You have the body, but the lack of experience is the only thing (possibly) that will prevent you from taking the show. Other than that I could see you dominating future shows with your psyique and the knowledge/experience to back it up. GL