There's no word on whether when the new feature will be rolled out for the Facebook Messenger. The Delete Message option only deletes the sent message from the sender's end.
However, Jane Manchun Wong shared screenshots of the said feature. It might be fair to let the timer be activated as long as the message hasn't been read.
At the moment, the messenger app doesn't give you that option, if a user wants to delete a message, the message will only disappear from their inbox, the recipient can still see the message. The company first announced plans to offer this feature following controversy over some Zuckerberg messages that had quietly been deleted from recipients' accounts.
Facebook is initially declared that it would Add Unsend feature for everyone in April after it was revealed that message had sent by the CEO of Facebook Mark Zuckerberg to other users were removed from the user's inboxes while the older message that those users sent Zuckerberg were still there.
Wong explained that there is a time limit for unsending messages.
However, this feature has the same twist as WhatsApp. WhatsApp already incorporates the sent message deleting option. Instagram refers to the new feature as "Facebook Location History" and describes it as a method of tracking the Global Positioning System location of a user using Facebook's tools. To use it, you just have to hold the text you wish to delete and pick the unsend option to erase it from history. With the redesigned Messenger app, Facebook is looking to get rid of unnecessary features in favour of something simple, more meaningful. However, there is a period of time after you send the text to retract it.
Instagram has a similar feature.