Will I loose weight by following this?

OK I am a 16 year old teenager Male. Weighing 121kg 266 Lbs height 5.2 inches. I recently started a diet plan which consist of low fat foods which approximately give me about 1000-1200 calories/day. Which include grilled chicken, veggies low fat yogurt, milk and juices. Beside I walk 1.5 Km daily I have done it for a week. Now i want to ask will I loose plenty of wight till September 20th if i follow this plan. Please suggest some other plans or exercises if you can. Fitness expert can chat me on Skype if they want to. Thanks anyway.