Make messages start at bottom of window when conversation length is small

How can I make messages start at the bottom of the chat window/message list when the conversation is short? For example, in the readme example and the chat friends example, the first message sent is displayed at the top of the chat window.

Is it possible to instead achieve the behavior of most chat apps (telegram, messenger, etc.) where the messages always start at the bottom of the chat window, just above the input box?