Gabi, I only got down to 30min catnap as I found any less was defeating the purpose of "tying over till next sleep period", a sleep period of any less than 30mins didn't really help them until the next sleep period and we just went to 1 nap. So for example, this was our schedule for a long time (approximate and give or take 15-30mins):
6am - wake
9-9:45am - morning nap
1-2.30/3pm - afternoon nap
6.30 - bedtime
And then when the girls would refuse the pm nap on a 45min am nap, I reduced it to 30mins and our schedule was:
6am - wake
9.30-10am - morning nap
12.30-2 - afternoon nap
6-6.30pm - bedtime
And once they refused a pm nap on a 30min am nap, I went to 1 nap but offered the nap around 11am and started slowly pushing it until it was closer to 12pm.
When they were down to 1 nap, that nap was in the middle of the day and our A time was approx 5hrs in the morning and 4.5-5hrs before bedtime.
There is no right or wrong and there were many times I would offer a morning nap and they would just play and that would be our 1 nap day. I didn't take missing a morning nap as a sign that I had to go to "all or nothing" approach and just go to 1 nap. In fact, I did try that and it lead to some major overtiredness. Of course, it does work for some but didn't for us
How old is your LO and what is she doing at the moment?