Changing from bottle to sippy cup

Hi all

Just wondering how/when you changed from bottles to sippy cups/cups?

My DD is 12months and will happily drink water from a sippy cup/normal cup and I was thinnking of getting rid of the daytime bottles in favour of sippy cups. She has 2x 150ml bottles of formula each day (morning tea and afternoon tea before naps) and will sometimes drink all of it and sometimes not much.

We tried a sippy cup yesterday at afternoon nap time and she happily had a few sips and then put it down. When she got grizzly and ready for a nap I offered it again and she wouldn't take it. ended up giving her 100ml bottle, which she loved and then went to bed happily.

Just wondering what to expect and how to go about changing her over to cups.

Many thnaks :-)