Depends on how much conditioning you will require, and also it depends on how much discipline you have. As far as your training split, do what has got you there so far in the beginning, but as the wks go on you may find you’re diet stagnating, and so a change might be in order. The only thing I would recommend changing for certain is that if you are normally incorporating low rep sets stop doing these during this time, keep all your reps in the 8-15 range, and more importantly start upping the intensity as much as you can stand. Once you've reached the level of intensity you are comfortable with turn it up another notch.
Here is a basic over-view of how I diet down, it's a little longer then how a lot of guys do it, but I feel the extra time allows me to be more thorough and not have to worry about crash dieting at the end...but don't get the idea that it makes it any easier.
Diet starts 20wks out:
wk 1-4 cut out any extra food, kcl intake is at maintenance, cardio 5x wk 30min
wk 5-8 start cycling carbs 4 fairly low days, 1 almost 0 carb day, and one high day...fat intake remains moderately high except on high carb day. kcl intake is also slowly reduced each wk. Cardio is slowly increased to 1hr day
wk 9-12 carb cycling the same as wk 5-8 calories again lowered. Cardio upped to 1 1/2hr per day in 2 sessions
wk 13-16 carb cycling may add in 1 more 0 carb day if needed, cardio now at 2hrs day in 2 sessions
wk 17-19 will eliminate high carb day if needed at wk 17 will end it for sure at start of wk 19, cardio still at 2hrs day
wk 20 cardio stops with Wed being last day. Training is stopped by Thur. Training for this wk is 2 days upper body 2 days lower, last lower day is done Wed...you don't want sore legs going into show Sat. These training sessions are more brief then normal almost circuit style
Here is a more precise breakdown of final wk:
Sun, Mon lowed up on sodium intake, as well as increase water by a lot, and I mean a lot, carbs are low
Tues, Wed, Thur, no carbs, no sodium, water intake decreases each day from here on out.
Fri morning, begin carb loading, you think this is an enjoyable thing, but you're hardly drinking any water, so it sucks.
Sat, do show.
If any of this is unclear or confusing let me know
Congrats on wanting to compete, and good luck to you!