Many people knew how big the world was at time of Columbus. Using that knowledge and knowing how long his trip was, how widespread among academics and scholars was the belief that Columbus had not actually made it to Asia early after his first voyage?

I've answered a similar questions already before.

Basically, European scholars back then did not accurately know the circumference, and did not know how big was Asia. They did suspect it was much less then Columbus' proposal, but they did not have a way to be sure.

That being said, there was a certain suspicious that Columbus did not reach Asia. Some because they didn't believe his calculation but more so because there was nothing he found there that could be connected to little they knew of Asia.