Adjustment of Status - I-485

I had my interview yesterday, the guy was friendly, a nice guy. He didn't really put any effort into trying to ascertain if the marriage was real or not, perhaps it was obvious to him from our original I-485 evidence submitted. He just asked for doc after doc for his checklist, what he asked for is below.

He didn't fingerprint or photo me or my spouse which was a little concerning and he forgot to ask for a few things, we had to volunteer them and he was like 'oh yes, I need that'. From memory, it kind of went like this;

Arrived 40 mins early
Taken into room about 90 mins after original time slot.
Sat us down in order he wanted
Stood us up to take oath
Asked for an initial set of documents (see all below)
Asked us what our name was, spouse's name, dob, place of birth - to each of us
Asked if we'd been married before, how many times we'd been married. He asked these at least twice each like he wanted to catch us out
Asked us I-485 yes/no questions
Moved onto relationship questions like, where do you live? 'How many children do you have together' and when we told him 1 he said oh, do you have the birth cert so I can skip most of the questions and after that he just asked us the same 3 questions about our child's name, dob and birth hospital.
He asked if we have any questions for him at which case we offered the further docs such as the I-693 which he then opened looked over.

Overall the interview took about 10 mins and we got the standard white paper saying our case needs to be reviewed at the end but he said everything looks good. He said he has to do a background check on both of use before he can approve so it takes some time, something new apparently and I have read about this being required by the current administration so I believe him. He said the white paper says 120 days but it should be about 75% of that (so 90 days I guess)

List of docs requested in which we had original and copies of:

Petitioner Photo Id (drivers license)
Beneficiary photo Id (passport)
Marriage cert
Petitioner proof of US citizenship (passport)
Beneficiary birth cert
Child birth certificate
Proof of financial relationship (gave him joint checking account statement and joint taxes for last 2 years, the latter he asked if we had so sounds like that's the best proof to have)
Proof of living together (gave him current joint lease)
Photo of us 2 with baby and family
Photo of us 2 alone

Now I suspect I have a 3 month wait to get the card.

Advice; take water and snacks if your appointment is midday. There we're a lot of us who has been waiting around for a while and you're too worried to leave the room/floor to go buy something in case you get called.