@ARMaliq Thank you! Actually not so many times, there were some activities on the last days before the 4 month deadline, but really not much. The only useful thing for mondossier is to see if your nationality has changed to Belgian or not on the first page. If you live in Brussels then you can also check IRISBOX, you should be able to download your Belgian certificate there.
The crazy thing is that although it has been more than 7 months, I have never received any letter officially to say that I am Belgian lol, I only knew it cause of IRISBOX. and then I went and applied for an ID and Passport immediately.