Working out 4 times a week. How soon will i see results?

I joined bally total fitness in July. I'm going 4 times a week, 2 of those days are with personal trainers. I have a very important event coming up in mid august. How soon will i see results. I started at 136....now I'm 140...im hoping thats muscle because I havent changed my eating. So how soon will i see results and should i change my eating. In the morning I eat special K cereal. For a snack i have yogurt, Lunch usually a salad or a protein bar with a banana. Another snack, yogurt or nuts. And for dinner chicken strips with veggies or rice. Please help...Thanks =)