I've never heard of three months. Maybe three days. I always start mine out naked for a day or two. I've trained three thus far and they all figured it out in a few days. When you start them out naked it is so that when they pee pee or poo poo you can tell them what they are doing and then sit them on the potty immediately. They only need do it a few times to figure it out and then you go to teri cloth panties or just big kid underwear at that point.
Warning though. Don't use pull-ups for anything but trips to the store. Pull-ups confuse a child and they figure out soon that they are glorified diapers and will take weeks if not months to train. I've seen kids in pull-ups for a year or more at four years old. They are a terrible way to train a child.
Just get the teri cloth pants, plenty of carpet cleaner and paper towels. Carry the potty chair around the house and watch them for signs they are going potty. After a day or two naked you shouldn't have much trouble with going pee pee on the potty. The poopies take a little longer, but I think that isn't that hard if you keep a close eye on your child for a week or so. Figure out their routine.
Everything I've read lately says that mom's should start to try at around 18 months. I guess in Europe they never wait as long as we do here in the states. The conventional wisdom that is developing now says they longer you wait the harder it is.
I trained my oldest at 26 months in a week. My second at 28 months in about a week. The third at 19 months to go pee pee on the potty in a week, but poopies took about a month before she didn't have any accidents.
I wouldn't worry about her being too young. If she can say any word to get across that she needs to go potty, even if it is just holding herself...then you can train her. She doesn't have to be able to talk.