I am 15 y-o. I want to know how frequently and when during the day I should consume protein shakes for results

This is a simple answer. First off, protein shakes are for serious results for serious workouts. Three times a week honestly isnt enough to justify the use of a protein supplement unless these are three times a week for 3+ hours a session. If you want to make some serious gain, weight lift mon-wed-fri, and do cardio tuesday and thursday. Take the weekend off to rebuild your muscles. May i make a recommendation, work out a different part of your body on the weight lift days. Upper body monday, lower body and legs wednesday, and tone the entire body friday. Spreading your workouts like that make for the best results so your not overstraining the same group of muscles over and over. Couple that routine, with a healthy diet that a trainer can make with you, and you'll start truely seeing results in a little as three months. Stick with it all the way through.