Hi C.
First I don't think all babies need the same amount of sleep. I also don't think that because they sleep one day they should be sleeping every day. In fact one of mine slept 2 hours in 24 by then and ever since. MD always said nothing was wrong and he succeeded well. One of mine slept 5 hours in 24 and still is. The other two-- one sleeps about 12 hours in 24 still and the other sleeps normally 7-10 hours.
None of them were nappers because what little sleep they got especially by 2, I wanted to be at night. The sleeper of the bunch I put to bed between 6:30 and 7 and he woke about then also the next morning. That was also my first. Seemed simple.
Can you put her to bed earlier on days she doesn't sleep?
We had what I called quiet time instead of nap time. I sat down and read books. Sometimes I read 5 or 6, and sometimes the sleeper would fall asleep as I read slower. I never had one that you could say it is nap time and they would go lay down and go to sleep. All the rest would listen to those books and then be ready to play again. At first I think I put children's songs and rhymes on, especially at that young age. Sing song rhymes are good for them to remember, learn know. Reading is good it enhances their idea that reading is fun.
God bless
K. SAHM married 38 years adult children ---37 entrepreneur and coach, 32 lawyer married with our grandson, and twins 18 in college after homeschooling. one is an artist and taking a BFA program, the other is at another school taking journalism, hoping to go to the mission field.