How soon can my fiancé become a citizen after we are married???

My fiancé is under the DACA program and we are getting married soon & expecting our baby boy in July!

I’m not familiar with how long it takes to get a green card or become a citizen through marriage. Can someone please fill me in on all of the steps we need to take? We of course will have my families and his families help getting it done, but I’m very excited to marry my best friend & for him to be able to become a citizen so I am just curious if anyone on here has been through the same and knows!💗