Cat99, 2-3 hours sounds about right to me.
To sort DS's sleeping out we did daytime naps first, started with introducing a nap within two hours of his waking (he wakes at about 7ish and is back in his cot by 9) spotting his sleep signals meant it was easy for him to go down without falling asleep to feed so we started doing feeds after his naps rather than before.
I'm not a fan of CC so DP and I had to talk over how long we were willing to leave him before going to him, we agreed whinging was fine but as soon as he was actually distressed rather than moaning then one or other of us would go straight up to him and calm him. We used PUPD (pick up put down) to calm him.
Every day he goes in his cot at around the same time for his nap, if he doesn't sleep then we leave him there for 'sleepy time' and most times he goes down no problem. He started sleeping without needing help in the day within a couple of days.
Then we started on the night time routine. We moved his bedtime forward about an hour as he was so tired at bedtime he would fall straight asleep feeding and not really wake much when we put him down, so we wanted to make his drowsy rather than tired at bedtime.
He was having a shower then feed and then straight to sleep at about 7pm, now he has dinner and a feed at 5pm, a shower, a small feed after his shower and is put in his cot awake.
We read a story and make him happy and comfortable in his cot then leave. The first couple of nights he cried a little, we would go to him and calm him, then place him back in bed, we also left the lamp on as turning it off made him cry.
After the first two nights we had no crying, within 4 days he was sleeping through.
IMO, he just needed to be comfortable being in his cot and getting himself to sleep, in effect he was falling asleep then waking scared and anxious in a different place, alone, with an empty stomach. Now he wakes up in the same place he goes to sleep or has his down time, plus he doesn't associate a full belly or mummy with sleep so he is happy to go back to sleep without me.