The PM's announcement on triggering Article 50 of the Lisbon Treaty means the UK looks set to leave the EU by the summer of 2019.
Mrs May also promised a bill to remove the European Communities Act 1972 from the statute book.
She told the Tory Party conference the government would strike a deal with the EU as an "independent sovereign" UK.
But in a speech at the start of the conference in Birmingham, Mrs May said there would be no "blow by blow" account of the negotiations.
"Every stray word and every hyped up media report is going to make it harder for us to get the right deal for Britain," she said.
The repeal of the 1972 Act will not take effect until the UK leaves the EU under Article 50.
It will be contained in a "Great Repeal Bill", promised in the next Queen's Speech, which will also enshrine all existing EU law into British law.
This will allow the government to seek to keep, amend or cancel any legislation once Brexit has been completed. The repeal bill will also end the jurisdiction of the European Court of Justice in the UK.
Brexit campaigners have been calling for Article 50 - which begins a two-year negotiation process - to be triggered as soon as possible.
Earlier, speaking on BBC One's The Andrew Marr Show, Mrs May, who had previously only said she would not trigger it this year, ended speculation about the government's timetable, saying this would be done by "the first quarter of 2017".