The EU summit in which everyone minus the UK collectively decide their extension offer is today/this evening.
The Cooper-Letwin bill, having passed, essentially means May just has to say yes to the EU's offer for it to come into play. No further votes in the Commons required (unless i've misread the situation).
So we'll probably tomorrow sometime? I imagine the pound will be on the up, slightly, as and when May lets it be known we've agreed to the extension.