So far he's staying flat, probably propped up from the dry food, etc. I'd say you could test again at 4:30 PM, post here and then leave him without food after that until you test at 5 PM. We want to see if his BG will stay flat or even begin to rise without the assistance of food. If you dosed him at 8 AM, you're now a little past +8 as we call it (8 hours past the AM dose - we refer to times this way because there are people here from all over the world) and if he's still low that suggests a late/prolonged nadir which can happen when a dose is too high.
Sorry for all the poking you have to do but it's the only way to keep Buddy safe.