Yes, do continue to stimulate. If by no other reason, it makes your work easier, you getting some controle on where he is peeing, so he isnt soiling his bedding. Also, you want to get his nr 2 get going...I have a couple of questions that I'm hoping to get answers too. So the kitten is starting to pee on his own now but he still hasn't pooped at all. Do I still need to stimulate him after his feedings? The vet said that his belly was soft and wasn't concerned about constipation but should I still try to get him to go or just let it happen naturally it's been about 4 days but he pees alot.
A part of it is, if he is somewhat dehydrated, the poo will be harder than usual = constipation. As he now gets correct amoutn of fluids, he should soon begin with the proper production of wastes too.
Also, you can give a couple of drops of oil with his food with every meal. Its a harmless home remedy loosening constipation. Almost any food oil will do, but our recommendation are coldpressed organic style olive oil, rapeseed / canola oil or cocoa oil. These are healthy and nourishing foods by themselves, so its an extra plus.
If this doesnt works out, next step will be minerale oils. which is more potent, but the problem is to where find a food grade minerale oil... But this your vet promised to help you with questions if you had, so you can always phone and ask.