Sure. Go ahead. The
WIP forum can now be used to maintain a development log, so even if you don't have a playable demo, you could still use it to get some exposure and build some hype. You could regularly post to share your progress. But do it every few days instead of posting about every little change, so that it isn't annoying for other developers showcasing their games.
Some members prefer to build an audience by regularly posting about their games on their profile feed. Some do it by putting a link or a banner in their signatures. Unless done excessively, it works just fine.