How does the credit score of spouse affect mortgage loan rates?

I wish to buy a house with my wife as a co-borrower. Both are working. I have a good credit score. My wife has no credit card yet, never had it. So no credit history. What options do I have.
(a) We apply for a loan together, with my wife with no credit history
(b) My wife first gets a credit card through my credit card bank as an authorized user.
(c) My wife gets a card through my credit card bank as an independent credit user.
(d) My wife gets an american express/costco card.
(e) any other option

In above cases, how long would we have to wait for applying a loan to ensure that our scores are OK to get best loan rates.
We have no joint credit card accounts. My spouse does not have an alternate credit, except her salary based saving and checking bank account. Our
Rental and utility bills/accounts are all in my name.

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