How long will it take me to get a six pack? (photo included) Please help!?

M Asked: How long will it take me to get a six pack? (photo included) Please help!?

I'm a 21 year old male. 5'11" and 162 pounds. I really let myself go the past six months, and i've eaten nothing but junk food. I just got a gym membership, and created a cardio/toning/ab plan. This requires going to the gym 4X/week. Based on my picture, do you think I can get a 6 pack in 12 weeks if I eat healthy and stick to my diet? Is that realistic? I have a fast metabolism
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