my ds was 22 months when i started and he picked it up really quick, i use to read him a story called nappy duck and potty pig befor i started and when i did he realated it to the story which i then had to read while he sat there. he was very regular with his bowls befor i started and i think this made it alot easier. i also rewarded him with a small lollie every time he went and he soon got the idea, the only thing i recomand is start in summer that way its warmer on their bot and that you put your dd in the potty every hr dont ask her just say potty time, if you ask she will say no and thats when accidents happen, although they are going to any way.
You could even try to put the potty next to the toilet if you have enough room and go at the same time as her and it might encourage her.
Good luck with it all.