They’ll usually start showing signs early that they dislike certain food. My son is 15 months and he refuses to eat avocado, he always turns his head or pushes the food away in anger because he doesn’t like it.
My daughters 2 I know what foods she’s doesn’t like pizza nachos apples and now shes telling me what she wants to eat always asks for bananas in the morning avocado at lunch and spaghetti for dinner 😂
if a baby doesn't like a food they will turn their head and refuse to open their mouth. you should only be starting solids at 6 months so anytime from there onwards, a baby can show like and dislike