Tim Barrow, the UK's envoy to the EU, informed the bloc's president Donald Tusk on Monday morning that May will invoke Article 50 of the Lisbon Treaty-the official mechanism by which a member state withdraws from the union.
The process will give a negotiating mandate to the EU's executive arm, the European Commission, with chief EU negotiator Michel Barnier going ahead with the process of scheduling talks with his British counterpart, Brexit minister David Davis.
A two-year timetable is expected to be followed, meaning Britain's official break with the European Union should occur in March 2019. The legal process therein prevents formal negotiations for the proposed exit until after the British government officially informs the European Union of its intent.
The Scottish move seemed to catch Downing Street off-guard, and may have contributed to a decision to push Article 50 notification back to the final week of March.
Due to trigger Article 50, her office has said May will be visiting Wales, Scotland and Northern Ireland to hear the government's differing views on Brexit. Few see two years as enough time to agree one and Brussels wants to hold off starting talks until after a divorce deal.
When the Brexit vote occurred, many people doubted as to whether or not the United Kingdom was actually going to go through with the plan.
March 29-31 - Within 48 hours, Tusk sends to the 27 other member states his draft negotiating guidelines.
Prime Minister Theresa May has vowed for months that the country will trigger Article 50 by the end of March.
Northern Ireland's largest Irish nationalist party Sinn Fein also said that he wants a referendum on splitting from the United Kingdom "as soon as possible" to join the Republic of Ireland.
Government must "ruthlessly prioritize" other legislation to ensure domestic policy agenda doesn't suffer. Such will confirm May's October pronouncement that she would begin the process by March.
"Brexit will place a huge burden on both Parliament and Government departments", the report warns.
Sir Tim Barrow, Britain's ambassador to the European Union, sought to dampen growing Brexiteer enthusiasm to quit without paying "a brass farthing" as one Conservative MP put it.