I would like simulate appearance of publications in a forum and I need know what is the probability distribution of new question being asked in a forum. In my first simulation I used to normal distribution, but I think that the best distribution can be exponential distribution.
The exponential distribution might be a good starting point for the waiting time between new posts. This would be equivalent to assuming a Poisson distributed number of posts in a given time period. There are some pretty strong assumptions behind a model like that, but it might make sense for your application.