If we don't get the extension we'll have to revoke.
The withdrawal agreement will take months to get through parliament because of Saturday.
Election vote tabled on Monday night
Election vote Tuesday
Polling day announced Wednesday
Parliament dissolved the following week.
Polling day December 12th
December 12th is the first Thursday they could hold the election, but if they don't mind having it on a Monday they could have if December 9th
Seriously, though, how careless you have to be to end up with an election in the middle of December