Are you asking when YOU will notice a difference or when someone else will?
I started lifting when I was perhaps 24 years old (back in the mid 90's to date myself) at the beginning of the summer. I was house sitting for my parents and spent the summer lifting and eating. I was a bit skinny fat (6 feet tall, about 160 pounds) at the beginning of the summer. I didn't really notice a lot of difference between the beginning of the summer and the end of the summer. My parents, however, on returning asked "Are you on steroids????" as I had blossomed up to 170 pounds and much leaner. It was a shocking transformation for them, but not a transformation at all for me (all that work and 10 measly pounds!).
That being said, you should probably be following the mantra of "Form follows function". Get strong, and you will get bigger. Track your lifts. If they are going up, then take comfort in the fact that you are probably getting bigger too. If they aren't going up, then eat more food.