Brexit negotiations had been expected to begin next week but May's loss of her parliamentary majority in a general election last week raised doubts about the date.
The Chancellor had been due to use a high-profile speech in the City of London on Thursday night to send out a message the Government would protect business from shocks during the Brexit process.
Since her gamble on a snap election failed a week ago, May has come under pressure from some in her own party to change her approach to Brexit talks.
Brexit talks in Brussels on Monday will focus on the status of expats, the UK's "divorce bill" and the Northern Ireland border, rather than on future trade relations with the European Union, it has been confirmed.
Prime Minister Theresa May in March formally notified the European Union of its intention to leave, starting a two-year timetable for negotiating the exit.
He wouldn't be drawn on whether he supported Britain's continued membership in the single market and said May's minority government will negotiate in a "pragmatic" manner, striving for a solution that works for both sides. The talks are taking place three months after Prime Minister Theresa May formally triggered the two-year Brexit timetable.
EU, UK fix date to begin Brexit negotiations
But the Government will press ahead with the first round of Brexit talks two days before the official opening of Parliament. Brexit is withdrawal from the European Union - it's the UK's decision.
"As we enter negotiations next week, we will do so in a spirit of cooperation, taking a pragmatic approach, trying to find a solution that works both for the United Kingdom and the European Union 27", he told reporters before a meeting of the 28 EU finance ministers in Luxembourg.
May's finance minister, Philip Hammond, said on Friday that Britain should prioritise protecting jobs and economic growth. Britain will be the first member state ever to leave the bloc.
"Our view is that withdrawal agreement and terms of the future relationship must be agreed alongside each other", said the spokesman.
"I'm not going to give a blow by blow account of how we propose to take that discussion forward", he said. "The withdrawal and future are intimately linked".
European Union leaders have given chief Brussels negotiator Michel Barnier no authority to so much as talk about future trade with Britain until he clinches outline deals on Brussels' priority issues, including London's exit bill.
Her spokesman said Britain would not change its stance on Brexit, though May told her lawmakers she would seek a broader consensus in the party on her approach.