Hello guys. Thanks for the help.
I contacted the helpline for national insurance number through telephone. They told me that this is neither my NINO nor a temporary one.
Is just a Tax Reference Number that they use internally to refer to me. As I asked why it is mentioned as a "National Insurance Number" in the paper, they answered me that this is a "mistake" because they still use the same templated for the letters they send.
So there is nothing I can do and I still wait my NINO in the next month.
Thank you for the help, I hope I also helped you with the answer.
Cheers