Unfortunately it looks like that will no longer be happening. According to an update on the Stardew Valley website, the developer has announced that the beta will be delayed. According to the post, “We had been planning to launch a multiplayer beta before the end of this year, but we’re pushing that beta back to Q1 2018 in order to make room for polish and QA.”
We suppose that is a fair reason for the delay, although we’re not sure if the delay of the multiplayer beta could also mean a delay for the actual release, which at the moment is still anyone’s guess. In the meantime the developer had also previously announced that they are working on more single-player content, so hopefully that will be enough to tide gamers over until the multiplayer feature is released, which at the moment still does not have a specific release date.