Wa'alaikumassalam! Aah, at 6 months when you introduce solids and formula, constipation memang common la, a few of my mum friends ada yang sama situation jugak. Normally every 3 days pun okay pa, as long as the poop is soft and baby doesn't struggle or seem uncomfortable, tapi best la check with your pediatrician just to make sure, esp. since you just started formula gak. Sementara tu, make sure baby minum enough water antara feeds, and kalau ada, try add pureed pumpkin or prunes into the solids, really helps dengan bowel movement. How does the poop look when dia goes, keras ke or still soft?