I wouldn't use any big girl pants until she masters going potty when naked and then loose pants only (no undies). I started introducing big girl pants after 4 weeks. They feel too much like nappies and muscle memory might trigger accidents in them
Truthfully, we’ve got our daughter in pull ups. Anytime that she has something to eat on drink, we will wait 30 minutes before having her go potty. I have an alarm set for every 30 minutes. When the alarm goes off, I tell her it’s time to go potty. I get up and go to the potty with her and sit there with her until she goes. We have tried to put her in big girl panties but she’s went in them so we went back to pull ups. When she wakes up from her nap, I’ll ask her if she’s got to go potty and she’ll tell me yes. She poos in her pull up from time to time but we are working with her on that still. Hope this helps! 😊