Yup, be careful what you wish for...it'll suck up your alk/ca so quick once it really starts growing. When you're trying to maintain an SPS-dominant tank, the last thing you need is something non-SPS sucking everything your SPS needs.
Basically, just keep your alk/ca levels up, and the coralline will grow. How fast it spreads will depend on spore count, flow, etc. If you want it everywhere, just scrape it off regularly, and it will spread.