Major steps forward in Welsh education will not be seen until reforms are fully in place after 2022, the chief inspector of schools said.
Estyn boss Meilyr Rowlands said parents would not see significant improvements until a new curriculum is rolled out.
In the most recent international Pisa tests, Welsh pupils scored lower than those in any other part of the UK.
Mr Rowlands said the new curriculum would be the biggest programme of change in decades.
“I can’t underestimate how big this change is,” he said.
“I would say it’s the biggest programme of change in education in Wales in my career.”
“We’ve seen some incremental improvements currently but in order to see a big step change we need to see all the reforms in place.
“So we’re talking about 2022 by the time that the curriculum is beginning to be rolled out in schools.”
The new curriculum will be introduced for nursery to year seven pupils in 2022 and will see a move away from narrow subjects to broad areas of learning with literacy, numeracy and digital skills embedded in all teaching.
Mr Rowlands said he was optimistic this would lead to a positive shake-up.
However, he warned a balance was needed between moving quickly enough for parents, communities and teachers to see progress, while making sure that the pace of reform did not put too much pressure on the system.
He described funding as “not the most important factor”.
“Whatever the overall level of budget it’s better if that was kept constant,” said MR Rowlands.
“I certainly think that consistency of funding would be something to aim for if at all possible”.
A review of the inspectorate Estyn earlier this year called for a move towards more schools evaluating themselves.
Mr Rowlands denied this could lead to a drop in standards, saying: “In many ways it’s a strengthening of accountability because what you’re doing is putting in place a self-evaluation system.
“That’s much more extensive in a way than the inspection system that we currently have.”