My 20 month old is having anywhere between 1 hr - 3.5 hr sleep in the day. He goes down when he is tired, rather than by routine. Sometimes it is before lunch (about 11.30) sometimes after lunch anywhere up to 3pm. But he also doesn't go to bed until 9ish at night, so I know we aren't typical. He doesn't wake up until 7.30ish in the morning so having a nap any earlier really wouldn't achieve anything for him.

But I would try watching her and seeing when she is naturally getting tired (if it all) and see how she goes if you put her down for a sleep at that time. What time does she get up? What time does she go to bed at night?