Theresa May began Britain's "momentous journey" to leave the EU by signing the letter that will trigger Article 50 on Tuesday.
The historic document will be delivered to the European Council in Brussels by the British ambassador to the EU, formally beginning the UK's departure from the EU.
Here is a timeline of the key events in the triggering of Article 50 which will take place on Wednesday:
8am - Cabinet will meet to discuss the letter which Theresa May signed on Tuesday which will start Britain's exit from the EU.
12.30pm - British ambassador to the EU, Sir Tim Barrow, will deliver the letter to European Council President Donald Tusk in Brussels. When Mr Tusk accepts the letter, Article 50 has officially been triggered.
12.30pm - After the weekly Prime Minister's Questions, Mrs May will make a statement to MPs confirming the beginning of the two-year Brexit process.
12.45pm - Once Mrs May has finished her statement, a text of the letter will be released. Copies of the letter will also be sent to the leaders of all other 27 EU member states.
12.45pm - Mr Tusk will make a statement in the Europa Building to reporters.
4.15pm - European Parliament Brexit negotiator Guy Verhofstadt and its president, Antonio Tajani, will hold a press conference.
4.30pm - Although European Commission President Jean-Claude Juncker is holding a press conference on EU issues not related to Brexit while on a visit to Malta, it is likely he will be asked about the start of Britain's departure from the bloc.
Within 48 hours of Article 50 being triggered, the European Commission is expected to issue "draft negotiation guidelines", which will be sent to the 27 remaining states for consultation.
Their leaders will meet on April 29 at an extraordinary European Council summit to agree a mandate for chief negotiator Michel Barnier and clear the way for talks to begin in earnest in May.
On Thursday, a white paper will be produced on the Great Repeal Bill, the legislation that will turn more than 40 years of EU regulations into domestic laws.
Over the next two years, the terms of the settlement will be thrashed out between Britain and its 27 counterparts.