March 12th (or earlier): Second vote on May deal.
March 13th: Vote on No Deal if WA fails to pass on the 12th
March 14th: Vote on an a50 extension.
The March 14th vote is the most important, though the others are still important and we have no idea how nuclear the ERG or the moderates will ultimately go in terms of blowing the Tory Party apart.
Even if May's Deal does pass we need an extension. We've known this a long time, from a British POV, but the EU have now explicitly said that they will need a technical extension to ratify the WA if we now approve it. We also need an extension if we decide to go for No Deal because we will have legal chaos as the HoC hasn't passed the necessary legislation for No Deal either. But this isn't the EU's problem...
With feelings in the EU becoming more bitter the idea of an extension might be more difficult to come by, if May hasn't passed the WA by the 29th March though.
The EU and May are therefore both aligned with a mutual interest to get the WA passed by 29th March for this reason. Which might mean the EU do play tough on granting us an extension (at least initially) if we formally ask for one on the 14th March in order to help persuade the HoC vote for May's deal before the deadline of the 29th March.
I think we should expect the WA to fail to pass on the 12th March. There just aren't the numbers for it. Then hardball politics from the EU commence on the 14th - it might well be a long extension or nothing. May will then try and do MV3 before the 29th March. If it passes, May's happy and the EU are happy. If it fails... well... I think the EU might give way to a shorter extension at that point, but very begrudgingly. And the idea will be for MV4 or the July cliff edge.
Until then we sit waiting forever for the sun to start going around the earth and for pigs to fall out of the sky.