When did you baby start sleeping through the night

My baby is EBF which I’m sure is part of the reason why but she will be 3mo next week and still waking up every 3hrs at night. I work full time and can’t keep up with the night feeds and no sleep much longer, so I do plan on trying to sleep train. I just don’t know what age to really start it. I don’t want to mess her up developmentally but I don’t want to have one of those babies who are still waking up multiple times at 6mo-yr old when they really don’t NEED it at those ages.