Mine went 5-6 days at the most when she was EBF, but my HV told me she had one mum whose baby used to go around every 10-14 days and was perfectly fine ... apparently though, when it was poop day, the poor woman didn't even leave the house as her baby would do so much poo! Lol.
If your baby seems happy I wouldn't worry too much, assuming he goes in the next couple of days. As long as it's soft and there's lots of it when he does go, then it's fine.