king577 wrote:I mean I replied before it was scheduled to be posted.
Yes, you were supposed to see that message.
I disallowed replying to future topics before they reach their scheduled post date/time because the post times of the replies to a future topic would be out of order, and it would just end up complicating things. You can reply to the topic once it reaches its future post time, but until then the topic is considered "non-existent" even though moderators can still see it.
By the way, this MOD allows you to schedule topics for posting in the future, but not regular reply posts. That is something I plan on adding as a new feature to this MOD in the later future.