By law, Parliament has to be dissolved 25 working days before a general election.
This means that time is running short for an election to take place comfortably before Christmas.
If MPs voted to trigger an election on Wednesday of this week, dissolution could follow immediately on Thursday, meaning a general election would take place on Thursday November 28.
But this timescale is very tight and would probably require the Government to put down a motion today calling for a vote tomorrow.
Another scenario would see MPs holding the trigger-vote at some point in the next few days, with dissolution pencilled in for October 31 and polling day on Thursday December 5.
The latest date for a general election before Christmas is probably Thursday December 12.
For this to happen, Parliament would need to be dissolved on November 7.
Any later and polling day would end up falling in the week before Christmas.
Alternatively MPs may decide to sit tight and wait until the festive season is out of the way before triggering an election, with dissolution potentially on January 9 2020 followed by polling day on February 13.
These scenarios assume that polling day would, as is tradition, fall on a Thursday – but there is nothing in law to stop it being on another day.
For example, if the trigger-vote did not take place until Monday October 28, dissolution could potentially follow on October 29 and polling day would be Tuesday December 3.
It is likely MPs would still want to pick a date that avoided clashing with the run-up to Christmas, however.
The last time a general election took place in December was 1923.