For how long of doing exercise will I notice an increase in my muscle?

I been doing excercise for the last 3 months. I do bench press and leg excercises and pushups almost every day for 30 minutes. I do 4 sets of 10 repetitions for each exercise. But I have not seem any results. I am a thin person that weights 155 lbs and my height is 5.8. I am 22 years old. I would like to know if I keep doing these same exercises, in how much time will I notice that my chest starts getting bigger. Thanks and please help!