Questions on CPR number and Procedural Visa?

Hi my name is John. I am a New Zealander which currently residing in the Faroe Islands.
Me and my wife(Danish) will moving to Denmark this year and I will be applying for the Family Reunification Visa once we arrive there.

I have read up on Family Reunification visa and understand that once immigration has accepted my application for processing, I will be given a procedural visa which would let me stay in Denmark while immigration process my visa.

My first question is, does anyone know how would the applicant made aware once they are on procedural visa?

Also, when can i apply for CPR number? once i get the procedural visa? or once the Family Reunification Visa has been approved?
Listed are the requirements for to get a CPR number
*You are staying in Denmark for more than 3 months (I will be staying because my wife will be studying in september. I can also stay in Denmark for 90 days visa free and will be applying for the Family Reunification)
*You hold a residence permit, if you are a non-EU citizen. (This is the confusing part, because reading up on some blog/article online, some has stated that i should apply for CPR number straight away once I get to Denmark)
*You have a place to live. (We got one of those student apartment.)

I have called the CPR hotline and the person couldn't give me the answer and suggested to call the immigration.

Any help/clarification is greatly appreciated, i have called the immigration and CPR hotline and both have pointed fingers at each other so i am abit lost.

Thank you in advance.

John