my kid is going to be 3 and he hasnt be trained to use the potty. everyone has a different opinion on this but ultimately you're the mother, you do what works for your kid and you. people can talk but they cant force you to do things you're not comfortable with. there's no proper timeframe on when to do it but best they're being taken off diapers by the age of 5 years old.
understand your frustrations. maybe try asking your husband to tell her to not force your son to do potty training. caning is definitely not the right way to teach potty training.