I am 17, weigh 203, 5' 11", I start firefighter school in 7/8 months, Whats my best chance of survival?

Should I lose the chub that I have on me right now which is about 20-30 pounds and then bulk up or should I bulk up now. I bought $150 worth or protein and creatine a year ago that I never used so its ready to go, but Im not sure I have 7 months to get into great shape and Id like to get the ball going faster and maybe get beach body before summer. I plan on joining the marine corps when I graduate which is in a year and a half so ill need to be in TIP TOP Physical condition for that so should i go skinny then buff or just keep adding on the pounds now?