4months baby can start eating or 6 months would be better to start?

Either is fine: babies usually start taking an interest in real food between 4 and 6 months. They should continue to take breastmilk or formula until 12 months and can add other foods like iron fortified cereals, fruits, veggies and meats around 4-6 months. Here is a link with lots more details. https://healthychildren.org/English/ages-stages/baby/feeding-nutrition/Pages/Switching-To-Solid-Foods.aspx

Birth, but: Fifty years ago some kids were fed solids as soon as they got home because the home made formula was better for cows than babies.Now that breast feeding or modern formulas are here, they do not need anything for the first year.Most recommend they start after they can sit up and the tongue thrust fades at 6mo.