I'm with Spotty. When DD was 4 months old and waking for feeds twice in the night, her paediatrician said "Either you sort out her sleep before 6 months, or don't be too sad if she doesn't sleep through the night until 2 years". DH and I were so scared at the prospect that we stopped night feeds that night. DD cried quite a lot that night, less the following night, and slept through (7-7) on third night and ever since. She is now 4 and goes to bed with a smile, snores like a piglet, and wakes up with a smile.
We did the same with DS, although a bit later. At 5 months, I stopped night feeds and DH went to him when he woke in the night. We fully expected him to sleep through in a few nights like DD but were horrified to see weeks go by and DS STILL waking up once in the night around 4 AM and not going back to sleep for about an hour. After a month of broken sleep, DH was a zombie.
All this time, DH was going to DS when he woke and cried, rocking him, hugging him, whatever. It turns out that this was what was keeping him awake. I am a much heavier sleeper than DH, and it was only when he was away for a few nights that DS started to sleep through. He must have woken up and cried for a bit, but because mummy didn't come, went back to sleep.
So now (6 months and a bit), DS has breastfeed at 6:30, bath, then a top-up bottle at 7:15 or so. I kiss him, sing "Twinkle", and put him in his cot. He hugs his bunny and puts a bunny ear in his mouth and off he goes into sleep. He wakes up between 7 and 7:30.
Moral of the story: Don't be afraid of a bit of crying.