Will it take me long to lose the weight?

ok i weigh 182lb and i want to lose 50lb to get to my normal weight...for my diet im walking 4 miles a day...drinkin non stop water and eating a slice of toast for breakfast and a salad for dinner with no dressings...i am sticking to this habit...how long will it take me to lose the weight...i only eat this amount as im not eating after 6pm ...