DS is 23 months and I'm sure he no longer needs his day sleep. Most days he fights it, often until we give up and then will sleep 6.30pm - 7.30am. He's perfectly cheerful without one and will most of the time even stay awake in the car.
If he does have a sleep - even if it's only short, he will be up till at least 9pm, often 10 or 10.30pm. Then he sleeps in the next day till 8.30/9am which doesn't suit me. If I wake him early at 7, in hopes he will be tired enough for a day sleep - he fights it even more because he's overtired and we have a day like today where I battled with him to nap for 90 minutes before driving him to sleep at 2pm.
Bit of a long post, but is 23 months too young to drop the day sleep? I know with a newbie arriving any day I should persist, but it doesn't seem like the trade-off is worth it.