I forgot to mention - even though Pierre has encouraged you to start posting stuff on ArtStation - I would HIGHLY recommend you hold off on things which are still work in progress. If they're pretty much done, post away but don't rush posting work that isn't representative of the final product. Like I briefly talked about you don't want to include a half baked piece in your portfolio (which should be reserved only for final work) as it'll end up bringing down/sabotaging the rest of it.
The easiest way to think about it is: you're always judged by your worst work.
But definitively start uploading!