Sometimes Oliver doesn't want to eat as well. He hasn't ever been on anything but dry kibble so I don't know how to help you there, but when Oliver is having trouble wanting to eat I make him do commands and treat him with the kibble, or hand feed him until half of it is gone and eventually he will just eat the second half on his own.
IMO, if you start him with gravy you will just have to end up weening him off the gravy as well. My buddies pup is 3 now and has to be starving to eat just plain old dry kibble.
Howdy from Idaho!
Oliver Kahn der Fasan Suchenden