How does it take to get workout results?

During the school year the gym class i took was personal fitness (weightlifting, cardio, etc...) and i took it twice a week for about 45 minutes. i clearly got stronger but i didnt notice any major changes with my definition. after school ended i joined my local gym and i have been going 3 times a week for about 1.5- 2 hours. its only been a couple weeks and i do a pretty complete workout when i go (it push myself until it really burns) i am just wondering how long it will take to see significant changes. i would like a professional opinion from this because everyone works out differently