My baby is 5 months old. He passes stool once in 3-4 days since a month. Is that normal?

If your baby starting his solid already, dont give him too much fiber like veggie but a good composition of carbo, protein and vegie and lots water. PD said 2.1l (if not mistaken or 1.8l). I went to PD specialized in nutrition and spent 250plus dol so anyone who has similar problem can try the suggestion first.