My twins are 15 months old and sometimes they have one nap days, and sometimes two. I found they were not ready for everyday to be a one nap day.
I try to workout away from home twice during the weekdays and they are in a very active daycare during that time, from 9 to 10:30 . I give them lunch before we leave because they fall asleep in the car on the way home about 11. They easily go into their cribs without waking at home.
It was a transition at first. They had to learn to sleep longer when taking one nap. Somedays it worked, others it didn't.
On days they took two naps they usually went to slept around 8:30 - 9 and 12:30 - 1:30. If I put them down after 2:00, they didn't sleep well at night.
At night they go down between 7 and 8, usually closer to 8 on a 2 nap day and 7:30 on a one nap day. They wake anywhere between 6:30 and 7:30 am. When my daughter started to wake earlier we let her try and go back to sleep or brought her to our bed.
The thing I noticed most was that there was transition time making changes and just being flexible with my schedule & plans so they are not over tired. We put a swing in the backyard which helped to give me something to do with them late afternoons and early evenings when they were more tired. =)