How this free Threads post scheduler works
Draft a Threads post (up to 500 characters), pick a media type, choose who can reply, and set a publish time. The character counter is grapheme-aware so emojis count the way Threads enforces them.
Threads character limit (500)
Threads posts allow up to 500 characters, nearly double X. The counter on this page goes red the moment you exceed 500 so you know to trim or split into a Threads thread before scheduling.
Reply control on Threads
Threads lets you restrict replies to followers, only people you mention, or nobody. Pick a value here and Postmixr applies the matching reply_control field on the Threads Graph API at publish.