Thousands of four- and five-year-olds across Ontario will be starting all-day kindergarten for the first time Tuesday, but critics say the government still hasn't figured out the ABCs of the ambitious program.

While the initiative is aimed at putting kids -- and the province -- on the path to economic prosperity, the implementation "has left quite a bit to be desired," said Annie Kidder of the parent-led group People for Education.

Keeping kids in the classroom longer is a great step, but not all of them will reap the benefits of early learning outside school hours as the province was originally urged to do, she said.

"It's been very messy, I would say," she said. "It's great that what's there is there, but all the stuff around it is very, very messy."

About 600 schools in Ontario will have full-day kindergarten this fall, a program Premier Dalton McGuinty promises will be available to every child by 2015.

The self-described "education premier" forged ahead last fall with the costly project despite the economic downturn and warnings of a record-setting deficit, arguing it would make Ontario more economically competitive.

Once fully implemented, it will cost the province an estimated $1.5 billion a year.

Each kindergarten class will include a teacher, an early childhood educator and up to 26 children, which is above the current primary class cap of 20 to 23 kids. That will require hiring about 3,800 new teachers and more than 20,000 new early childhood educators over the next few years.

Parents can pay extra for child care before 9 a.m. and after 3:30 p.m., which would be staffed by early childhood educators. But it won't be offered at all schools.

The Ontario Public School Boards' Association estimates that only 10 to 15 per cent of schools will offer the after-hours program, with costs ranging from $22 to $30 per child per day. Schools needed to have enough space and demand from parents to offer the program.

The after-hours program was left for "the last minute," which frustrated many parents, Kidder said. Some parents were being asked to sign up for a service when they didn't know how much it would cost.

Extended child care was a key part of the integrated plan devised by the government's early-learning advisor, Charles Pascal. It's what "makes a difference" with kids, Kidder said.

Pascal's vision for early learning started at birth, expanding paid parental leave to 400 days, and combining daycare and kindergarten into a single full-day program from 7:30 a.m. to 6 p.m. to make life easier for parents and their children.

"Last year everybody warned, 'Don't cherry-pick from this plan. Don't just take one piece of it and do that. You have to do the whole thing,"' said Kidder.

"And it was hard. I mean, it's a big, ambitious plan. It was going to involve a huge amount of structural change. But what seems to have happened is that there was cherry-picking, with a focus (that) has certainly just been on the full-day kindergarten."

The province didn't provide school boards with the rules about child-care fees until mid-June, which created some consternation, McGuinty recently acknowledged.

"There are going to be a few glitches along the way, a few wrinkles that will develop, and we'll need to take some time and consult to address those," he said during a recent stop at a new elementary school in Kitchener, Ont., to promote the program.

Parents will likely be more aware next September of what's available to them and how much it will cost, McGuinty added.

Catherine Fife, president of the Ontario Public School Boards' Association, said there's "definitely interest" for extended child care, but the province has to try to make it more affordable.

"We've never done this before, so it's a learning curve for school boards as well," she said.

The scarcity of after-hours programming isn't the only problem with full-day kindergarten, according to opposition critics.

School boards are siphoning money from other areas in the scramble to fund full-day kindergarten, and some are finding it difficult to recruit early childhood educators, particularly those who speak French, said Progressive Conservative education critic Elizabeth Witmer.

In the end, parents aren't getting what they were promised, she said.

"The main objective -- a seamless school day -- has not been accomplished," she said. "So that is probably going to be very disappointing."

The New Democrats say full-day programming isn't available to many families who need it the most, because it's only being offered in schools that already had the space for it.

Even school boards that are "gung-ho" about full-day kindergarten are concerned about its implementation because they aren't getting the money they need to pull it off, said NDP critic Rosario Marchese.

"They're worried because if they do this program, something else may have to go," he said.