How long till I see results from probiotics

Today is day 3 being on 1/8tsp probiotics once a day. Was just wondering when I should start seeing some results? Good news is his gas has definitely gotten better but he still has runny poops, although he's now only going 2 times a day as opposed to 4-5 before, so I'm thinking it's slowly working. He's 10 months old and has had runny poops all his life so this is a trial since all tests come out clean and he's in perfect health.

It will take longer than 3 days to get full results.  You are trying to introduce strains of good bacteria into the gut.  The ones that survive stomach acid and make it to the gut have to take root and begin reproducing.