If you're skeptical, go with your instincts and ask her to stop if you want. She needs to follow your lead on anything to do with your son. It's interesting that she told you, rather than asked you, about her plans. Can he stand and walk any distance yet? Potty training usually follows after a child can stand, plus walk, sit when asked to, sense the urge to "go" sometimes even if he still goes in a diaper, can pull pants up and down -- nine-month-olds can't do all those things. If she's pressuring you (and him) to let her do this, is it just because it would be more convenient for her if he were potty-trained ASAP? Any day care provider should be willing to change diapers, then pull-ups, for some time to come -- and tackle potty training when he's physically and mentally ready, on his schedule and not hers, and when you as the parent and the employer say it's time.If you want backup for your skepticism when you talk to her about it, maybe try asking your pediatrician so you can tell her what the doctor says. I'd bet the doctor will say nine months is too young because the basic milestones that indicate a kid is ready to train are still a way off. Let us know what happens.