Most people who are "neurotypical" (not all) would, in an instinctual sense, KNOW when to start initiating a conversation. It seems to go "smoothly" with them.
Within SOME autistic people, there might be conscious thought involved, which doesn't occur with the "neurotypical" person---such as " I have to wait until the other person is finished before I enter the conversation."
Thus, the "transition" might not be go as "smoothly" as what occurred with the "neurotypical" person.