My (almost) 18 month old wakes twice most nights. He goes down in his bed first, and usually wakes and comes into my bed between 1 and 2.30am. He has a feed then and back to sleep. He then sleeps 3 hours ish, or lately has been starting to sleep til 7am ish. if he wakes the 2nd time, whether he feeds or not, he will usually then sleep in longer in the morning.

My DD started to sleep through 10 hours or so around 18 months, she had a waterbottle in her bed, and i'm hoping DS does soon too. She only had her first 5 hour sleep at 15 months, so big changes happened quite quickly, once she was ready.