Potty training continued

So it seems that Finn has no qualms with the peeing aspect of PTing. He wore underwear all day, peed in the potty, easy peasy. Poop however, is a different story. It took him 3 days to go the first time, which Jay just so happened to be bathing him and saw happening and sat him on the potty. Today (4 days since his last poop) he asked for a diaper late afternoon. I told him no, and stuck him on the potty, knowing he needed to poop. Nothing happened. A few more hours pass, and hes going outside to play with Jay, pees on the potty, and not 5 minutes later comes waddling back in with poop in the pants. We flushed it, and talked about pooping in the potty, he seems to understand, but for whatever reason understanding and doing are not meshing. I'm not giving up though. Its been super easy until now, and I don't miss having double the diaper laundry. I'm already 4 seconds from getting rid of all of Finns diapers.