XF 1.5 Only allow users to post one time in a forum?


I am seeking to limit people to only make one post in the "Introduction" forum.

The reason is that I am running a points system and posting in the Introduction forums gives a bonus. Also, obviously, you only introduce yourself once :)

Anyone has any idea how I can achieve that?
Im interested in learning and this looks like a simple enough starting project. Any pointers to get me started?

I would make the addon available for free to everyone once done.