Ken Corsar, director of education in Glasgow and a forum adviser, told the meeting in Glenrothes: "The new financial year is only eight weeks away and we are still uncertain as to the level of funding we will have. The details are sadly lacking at this stage."
So far, ministers have confirmed that pound;75.6 million will be available for the third term of the nursery vouchers and the two terms of grant from August. Some pound;50 million of this will be distributed to councils as grants.
Mr Corsar said authorities welcomed the thrust of the pre-five initiative and the control given to them but the nursery picture was still "very variable".
Across Scotland, 53 per cent of four-year-olds have a place, along with 20 per cent of three-year-olds. The Government has made a commitment to a place for all four-year-olds by this winter.
Mr Corsar said issues such as funding for special needs, transport for rural areas and Gaelic nurseries would have to be taken up with the Scottish Office.
Quality assurance and training were further concerns. Mr Corsar described the targets to place three-year-olds as "bold and ambitious".
Malcolm Green, Glasgow's education convener, welcomed moves to make pre-school education statutory but only after provision was on the ground. "That will make sure the money is not subsequently raided by future governments or local authorities," Dr Green said.