Benefit claimants struggling to pay their bills will be able to get cash advances upfront, Work and Pensions Secretary David Gauke has said.
He said he recognised concerns that people moving on to Universal Credit had to wait six weeks to be paid.
He told the Conservative conference those needing a cash advance would get one within five days - or on the same day in emergency cases.
But he said he was committed to the system and its rollout would go ahead.
A dozen or so Conservative MPs have called for the rollout of Universal Credit, which merges six existing benefits into one, to be put on hold because of the financial difficulties facing people arising from the transition from weekly or fortnightly to monthly payments.
Official figures show 24% of new Universal Credit claimants wait longer than six weeks to be paid in full - causing many to fall behind on rent.
The government has insisted the vast majority of claimants were paid in full and on time, and are comfortable managing their money.
Analysis by Michael Buchanan, social affairs correspondent
Claimants will now be able to get some money on the day they make a claim and ministers want more people to apply for an advance - rather than waiting at least six weeks for their first Universal Credit payment
Advance Payments are a loan. Claimants for Universal Credit can apply for a proportion of their expected award to be paid to them before their first full payment.
They have always been a part of the Universal Credit system but many people have claimed they weren't made aware of them.
The advance payment is automatically taken out of any subsequent Universal Credit payment over a number of months until the total amount is paid off.
Mr Gauke told party conference in Manchester that the shake-up of the benefit system was "working", giving people more incentives to seek employment and helping people in work secure better-paid jobs.
He insisted that its rollout to more JobCentres across the UK would continue on the present timetable, with the aim of it being fully implemented by 2022.
But he said the rollout would not be "rushed" and he had listened to concerns about how some new claimants were finding it hard to make ends meet.
"I am determined to ensure that those who need support earlier in the month will get it," he said.
"I can announce today that we are refreshing the guidance to DWP staff to ensure that anyone who needs an advance payment will be offered it up-front.
"Claimants who want an advance payment will not have to wait six weeks. They will receive this advance within five working days. And if someone is in immediate need, then we fast track the payment, meaning they will receive it on the same day."
The Child Poverty Action Group welcomed cash support for families with children but said wider concerns over the design, implementation and funding of Universal Credit were not being addressed.
"It does not make sense to pretend that having no income for six weeks won't harm them," said its chief executive Alison Garnham.
And housing associations said they still had real concerns about how families on low incomes would cope.
"DWP must help people make and manage claims effectively and swiftly," said Sue Ramsden, from the National Housing Federation.
"The money should be made available on request rather than be dependent on claimants having to demonstrate need."