Officals announced last week that babies, toddlers and children on some of Wales's toughest council estates would be signed up to the scheme, which allows children more scope to learn through structured play, from September.
The earmarked centres are all located in Flying Start areas where initiatives are targeted to help both parents and children under three.
They will be called Early Start Schools and Settings, and the learning through play curriculum is expected to run alongside the parenting classes, free childcare and health improvement schemes.
But Geraint Davies, Welsh secretary of education union the NASUWT, said the announcement was likely to send heads and leaders at the chosen settings into a state of panic.
"This is an admirable, exciting thing to do but it must be backed up with the right funding and trained staff," he said. "This is a huge challenge, especially in the areas that have been designated."
Mr Davies said many schools in Wales had still not made changes to their curriculum to cater for the foundation phase, despite a full roll-out from September 2008.
He said this was due to a lack of Assembly government guidance that was keeping schools and teachers in the dark. Last month Susan Lewis, chief inspector, said the pilot's progress was being hampered by a lack of guidance for teachers, although she praised staff for high teaching standards.
It is believed that the new schools and settings were only made aware of the intention to roll out the scheme two weeks ago.
But an Assembly government spokesperson said that guidance material would not beJavailable until January 2008 and that this was due to consultation now taking place on proposals for the Framework for Children's Learning in the foundation phase that had been scheduled with the autumn 2008 roll-out in mind.
Much of the foundation phase is focused on outdoor learning, with settings expected to have facilities both and in and out of the classroom. It has meant many nurseries selling up to find more suitable venues. But figures out last September showed that more than half of Wales's primary schools do not yet have enough staff to teach the curriculum.
There have also been question marks over the teaching of literacy under the new phase. A report out before Christmas by some of the Assembly government's closest academic advisers found the quality of literacy, communication and language teaching in the pilot schools had "significantly declined" last year, compared with 2004-5. More adult-guided learning was recommended to redress the playwork balance.
The new settings are a mix of English-medium, Welsh-medium and faith schools, playgroups, nursery and infantjunior schools.
New settings in the foundation phase
From September 2007
Ysgol y Graig Cylch Meithrin Stryd y Bont
Deighton primary school
Cylch Meithrin ABC
Blaenllynfi Infants Caerau nursery
Upper Rhymney primary
Cylch Meithrin Rhymni
Herbert Thompson primary
Cylch Meithrin Pila Pala
Ysgol Gynradd Bigyn
Myrtle House nursery
Ysgol Plant Bach Aberteifi
Cylch Meithrin Llanarth
Ysgol Babanod T Gwynn Jones Cadwgan playgroup
Gwynedd CP school Nippers Nest playgroup
Ysgol Gynradd, Maesincla
Cylch Meithrin Maesincla
Gurnos nursery school
Deri View primary and nursery Cylch Meithrin Y Fenni
Neath Port Talbot
Pillgwenlly primary Castleton Baptist Church playgroup
Pembroke Dock community school Tabernacle kindergarten
Maesyrhandir CP school
Trehafren children's centre
Rhondda Cynon Taf
Heol Y Celyn primary Cylch Meithrin y Ddreanen-wen
Townhill community primary school
Penygarn infants school
Buzzy Bees day nursery
Vale of Glamorgan
Cadoxton nursery primary schools
Ysgol y Gaer Bradley playgroup