Poverty campaigners have written to Nicola Sturgeon urging her to bring forward the timetable for a new benefit to tackle child poverty.
The Scottish government has said the family income supplement will be introduced in 2022.
However, charities have said this date is too far away and called on the first minister to introduce it sooner.
Ministers are due to update parliament on Wednesday about plans to "top up" the earnings of low-income parents.
However, campaigners hope legislation will be included in the next programme for government, with an interim version brought in ahead of legislation being passed.
A total of 70 signatories - including academics, children's charities, trade unions, women's groups and faith leaders - penned a joint letter which said the benefit would provide a "valuable lifeline" for 240,000 children living in poverty in Scotland.
SallyAnn Kelly, CEO of the children's charity Aberlour, said: "Waiting until 2022 is too late for many families who are struggling now and the 240,000 children living in poverty.
"Working with families across Scotland every day we see how many of them are at risk of falling deeper into financial hardship and being exposed to the worst effects of poverty and related toxic stress.
"The Scottish government must use the powers available to them before it's too late."
Peter Kelly, of the Poverty Alliance, added that urgent action was required, as "the equivalent of one classroom of children a day [is] being pulled into poverty in Scotland."
Commenting on the letter, Children and Young People's Commissioner Bruce Adamson said child poverty was "the most significant human rights issue facing children in Scotland".
He added that "living in poverty affects every aspect of a child's life", and that addressing the issue had to be a "priority".
Communities Secretary Aileen Campbell said the government's first Tackling Child Poverty Delivery Plan, published last year, "outlined the range of actions to be taken to help meet our child poverty targets, backed by a £50m fund".
She continued: "Our actions include working on development of a new income supplement and we have involved stakeholders, including Poverty Alliance and many of their signatories, in that work.
"A one-year progress report on the delivery plan will be given to parliament on Wednesday."