Co-sleeping and breastfeeding - when did yours sleep through?

[jurassicpark]

DS is 7mths and somehow moved from quite a good sleeper in his own bed to waking every 2 hours and sleeping in our bed (since 4mths). I like it as it means I don't need to properly wake to feed him during the night (especially since I have a dropping-the-nap toddler) but I would also like a bit, just a bit more sleep.
So, when did yours finally work out that sleeping is the bees knees, or did you end up having to do something about it?

DS1 at around ten months (he's now 8), DS2 (5) still wakes - is a terrible sleeper, DD1 (10 months) two weeks old. I just wish there was a way of guaranteeing if we have a no.4 they would sleep like DD1!

With DS2 I did do controlled crying to get him in his own bed through the night. We do rewards etc, he just doesn't need as much sleep as the others and is a light sleeper.

Is your DS sitting up/crawling? This might sound silly but DS (now 9 months) slept through from 1 week old but at about 4 months he started waking (a week or so later he could sit up) and at 7 months he started waking up lots. It would seem he was learning to crawl as he has just mastered it, spent one or two nights waking up all pleased with himself, practising it in the middle of the night and has slept through since. (He is in a bedside cot). I had heard this before but DD was such a terrible sleeper that I wouldn't have noticed the difference. She's 2 1/2 now and sleeps through and has done for a long time but I do co sleep with both of them.

DS is just getting the hang of sitting. Bizarrely the night I posted this he slept for 4 hours in a row, turns out he was on his front. Obviously I thought this was the cure but ever since just gets too upset when he rolls onto his front. Och well. Will wait for crawling to happen and teething to pass...