About one hour after asking a question, I found the answer on my own. I therefore wrote an answer to my own question, documenting the process. However, when I wanted to accept my own answer, I was greeted with a error saying there is a two days cooldown period during which I can't accept my own answer.
Now, if that's the rule, I'm fine with it (except that I risk to forget it, but that's my problem) but I was wondering what was the rational behind this. Is it to prevent self-promotion spam or something like this ?