My game Gold Miner will be going through many updates (Like most phone/PC games) so should I put it in the showcase when the first “full release” (non beta/alpha) or should I wait till I just quit working on the game and start a new project? ???
WIP is for work-in-progress games.
When you feel that the game is ‘complete’, in that it is a fully playable game, then you can choose ask the mods to move it to the showcase.
I already put my game in the WIP but thanks! 
Showcase is mainly for games which are finished and you do not really want to work on anymore.
If you are planning to keep adding updates it is the wrong place, if not officially at least because it is afaik sorted by first release date instead of last post in a thread…
The Showcase board is for playable games.
If you want to keep updating it after its release, that’s perfectly fine - even encouraged. Improving your game is certainly not frowned upon in the Showcase board, that would be silly.