card and caregiver questions

I have just moved to Montana and am going to the doctor tomorrow to get my recommendation. I know I will be approved as I have very extensive medical records from chronic pain. My question is about the time between the recommendation and actually getting a card. I have heard it can be up to 6 weeks. I do not want to go that long without as it a daily pain management issue. Are caregivers allowed to provide med with only a recommendation or do I need the card. Also do I need to know what caregiver to use as maybe some will allow this and some won't but I need to be able to put it on my form before I send it??

Any help would be great!