Changing sleep routine for 15-month old - any tips?

[sleepychunky]

Hi all, hope you can help.

DS has just turned 15 months and is a lovely, happy boy. He's been in the same routine for ages now (since about 9 months old) and I'm thinking that maybe he has outgrown it.
He's started to wake up much earlier in the morning now, and although it's never before I'm awake, it's still really early. He used to do 12 hours 7-7 but now it's 7-5.45 or 6 at the latest. He still has a couple of hours sleep in the day after lunch as well.
Does a 15-month old need 14 hours sleep in 24 hours, or should I cut back daytime sleep to an hour maybe?
Any experiences on putting back bedtime? I know I've read people saying that going to bed later hasn't made their DCs stay asleep any longer the next morning, but is it worth trying?
Thanks
SC

my 23 month old still has a couple of hours nap after lunch and is in bed for 7.15/7.30pm and wakes sometime around 6/6.30am although as he is happy to stay in his cot for a while after waking then I dotn go and get him till nearly 7am. I think the average is about 13/14 hours per 24 hours.

thanks - mine won't stay in his cot once he's woken though as he always wants a drink straight away.
Will maybe put him to bed just a little bit later tonight and see if it makes any difference tomorrow.