Marrying in Denmark, immigrating to Germany

My partner is American, I am German, we are planning to immigrate to Germany. As we are running out of time, he has about 40 days left on his tourist visa, we are planning to get married in Denmark.

- He has a valid US passport, A1 from Goethe, Birth Certificate

- we have an apartment with plenty space

- My income covers both of us.

If we get married on Denmark how many days do we need to plan to stay there to get married and receive the certificate?

Once papers received can go directly to the Auslaenderbehoerde and file visa under the familienzusammenführung?

If not what steps am I missing? I have seen some conflicting information and would love someone's experience on this.