once your kid feels comfortable to sit on the potty and you can catch his/her time to make "V V" (some kids make "V V" every 1/2 hour or 45 minutes or 1 hour), then he/she can try the trainer pant.
for your reference, my 1st daughter use the potty at 10 months, she then use the cotton trainer pant at home (I bought in Seiyu Shatin and Jusco) and Huggies trainer pant (paper one) when going out. She totally did not use any trainer pant at 2.
my 2nd son is now 2 year old, he does not know to say "V V" and that's why he is still using trainer pant .