It really depends on exposure and interest. I buy a lot of building toys because I feel they are really great for imaginative play. I did not start with wooden blocks because I wasn't sure if she would be chucking it at me. We have wooden blocks (passed down from my husband's grandmother who was really into architecture) but I think they must be for adults, the edges/corners are pretty sharp. So I waited until my daughter wasn't putting toys in her mouth anymore to show her those (I didn't want bite marks on them). She was not as interested in those as her other builders but perhaps if that was our only building toy, she would have been.
Her first builder toy was a Lego Duplo set around 1 year and 8 months as a Christmas gift. She played with that a bunch but the set didn't have much pieces. Then she saw her friends (who were 3-5 years old) playing with the "normal" Lego's. By 2.5 she was connecting her own Lego's that size and building stuff on her own. We never had to buy another Duplo.
I bought a set of Straws and Connectors by Royolco when she was 2 years and 1 month. It is amazing and was an incredible hit. She would put them in but I had to help make sure it was fully engaged. Eventually she was able to put them all the way in. She was building her own stuff by this point - nothing fancy, a "T" or "L" shape to make a steering wheel for whatever I had built but she knew what she was building.

My cousin had the Melissa & Doug play bricks (the ones you can step on) at her 2 year old's party and they were building roads with them. I really think it depends on how often they play with these kinds of toys.
Bricks
while Mega Bloks refer to their similar pieces asBlocks
.