The government plans to trigger Brexit by the end of March next year, and had previously said it would not declare its hand on the upcoming talks until then.
But on Tuesday, May agreed to publish her plan for leaving the EU in order to avoid a possible Tory rebellion and defeat in the House of Commons.
The government hopes that her move will persuade MPs to support its schedule for starting the process of leaving.
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Labour said it would back the timetable but wanted scrutiny of Brexit plans.
The party's shadow Brexit secretary Keir Starmer put forward a motion, due to be debated on Wednesday, with support from some on the Conservative back benches.
Jenny Chapman MP, Labour's shadow minister for exiting the EU, said, "The fact is, their plan for Brexit is completely blank.
"Every indication so far is that the Prime Minister will seek a hard and damaging Brexit, with Britain outside the single market and the customs union. This would be bad for the economy, for business and for jobs.
"What we need to see is a plan and a strategy, and the Ggvernment seeking to build consensus around it. They can do that by publishing their basic plan before article 50 is triggered, as Labour will again be calling for on Wednesday."
James McGrory, co-executive director of the group Open Britain, which has grown out of the official Remain campaign, welcomed May's decision but warned that the devil would be in the detail.
He said: "The plan they bring before Parliament should be substantive and it should be given proper time for debate."
Meanwhile, the UK Supreme Court hearing on Brexit was told that parliamentary legislation that paved the way for Britain to enter the EU is being treated with contempt by ministers who regard it as "less important than the dangerous dogs act."
Lord Pannick, opening the argument on behalf of the lead claimant, Gina Miller, dismissed the government's assertion that it was entitled to use its prerogative powers to deliver notice of the UK's intention to leave the EU under article 50 of the treaty on the EU as "inherently implausible."
Pannick, an expert in constitutional law, emphasised the unique qualities of the 1972 European communities act, which prepared the way for Britain to join what was then the European Economic Community.
"The courts have repeatedly recognised that the 1972 act has a constitutional status," Pannick told the justices.
"It created a new source of domestic law and granted priority to it. The government's argument if followed should mean that the act, far from having a constitutional status, would have a lesser status than that of the dangerous dogs act."