I got 12 weeks with both kids. My first was a great magical unicorn sleeper, and I felt fine and ready to go back at 12 weeks. In fact he started sleeping through the night (like 10 hrs continuous) around 3 months so I pretty much never had to work + do night wakeups at the same time.

My second was a more normal (maybe even below average?) sleeper. She was barely doing 4 hrs at 12 weeks, and in fact had a regression of going back to 2-3 hrs right when I went back to work. Adding in the general hecticness of dealing with 2 kids now...going back to work felt like 10x harder compared to my first and I definitely would've like a few months more.

So yeah...the answer is it depends.

Oh also my husband also had 3-4 months parental leave that he took after me, so my kids didn't go to daycare until 6 months old in both cases. I think I would've been less comfortable putting a 12 week old in daycare.