2 hours, OP. It was misery. And the next night 45 minutes, and the next 15. He still frets (whines or grumbles, not screams and cries) about 5 or so minutes when I put him down but he can settle himself, which is actually what we wanted to teach. He'd been a good sleeper till 3 months, when teething hit, and then he seemed to unlearn how to sleep.
After 3 months of 1-2 hour or 45 minute sleeps interrupted by having to nurse and resettle, I was the kind of tired that lies down crying. I was miserable, my OCD was getting out of hand. At my lowest point I texted a friend "I've ruined my life". It was horrible.
BTW, before we did it, he screamed and whined constantly, had no attention span, and seemed to hate everything. Now he's keen, curious, funny, and fun. Yes, he's still shouty, but it's a different, excited kind of shouty. It's great.
Good luck!