Hello! At the last pediatrician appointment, she told us that in Janua…

Hello! At the last pediatrician appointment, she told us that in January we will start talking about weaning, from what to start with. But in January we only have 4 months, we're on Gv. Also, my sister-in-law said that they introduce complementary feeding at 4 months. And I thought it started at six... How do you think this is right?