Our son is 2 years old as of September, and he's been trying to skip his mid-day nap lately.
What usually happens is at around 1-2 PM, he'll start to get sleepy. At this time, if we put on soothing music and reduce the light level in the entire house, and hold him in our arms, about 60% of the time he'll fall asleep. Even if he doesn't, we tend to put him in his room at this time anyway.
If if he doesn't nap, he'll stay up until 5-6 PM and fairly reliably go to sleep. If he does, he'll be up until around 10 PM, but usually sleep through the entire night. If he goes to sleep at 5-6 PM, he'll usually wake up once between 11 PM and 2 AM either for a diaper change or just to run around in his (toddler-safe) room, then sleep for the rest of the night.
Some days he seems to have plenty of energy to make it to 5-6 PM, other days it's clear he could really use a nap, but he just doesn't want to do so.
Should we encourage him to nap mid-day as much as possible, or should we encourage him to wait until 5-6 PM to sleep?
He's slightly delayed in his speech development, so he isn't yet able to vocalize his preference - though he will usually protest napping attempts if he's vehemently against the idea.