DID YOU KNOW: They were first called "Christians" at Antioch

"Christian" means "follower of Christ". So why did it take all the way until Acts 11 for anyone to call them by that name?

It is not obvious in the English, but Christ is actually a Greek word. The Hebrew (Jewish) word is "Messiah." Before Acts 10, all Christians were Jewish and considered themselves to be a sect of Judaism. Converts generally became circumcised and followed the Jewish Law. It was not until Peter's vision that it became clear that God had changed the rules, allowing all nations into his kingdom. Up until this time, tradition says that Jesus followers were actually called "Nazarenes" - referring to Jesus's home town of Nazareth. This reflects the Jewish scorn for the new faith - as Nazareth was generally viewed with scorn and therefore being called by that name was an insult.

Philip found Nathanael and told him, "We have found the one Moses wrote about in the Law, and about whom the prophets also wrote—Jesus of Nazareth, the son of Joseph."
"Nazareth! Can anything good come from there?" Nathanael asked.
"Come and see," said Philip.
John 1:45-46 NIV

So, when the disciples started being called "Christians", it marks the time when Gentiles (who spoke Greek) started noticing that they existed. It is another mark of the transition from the religion of Jesus being Jewish to being a world-wide religion.