A major promotion is planned for the spring, just over a year before the first of the new work-related alternatives to GCSEs and A-levels are due to start being taught.
Hundreds of secondary schools and colleges are likely to be involved in local partnerships to offer diplomas in five subjects - engineering, construction, information technology, health and social care, creative and media - from 2008. By 2013, there will be 14 or 15 diploma subjects on offer to every pupil in England.
A lot rides on the uptake of the exams, which are meant to place vocational qualifications on a par with academic tests. But they will have to compete with BTECs and vocational GCSE and A-levels.
More than 300 partnerships, backed by local authorities and employers, applied last autumn to offer diplomas from 2008.
These bids are being assessed, with government officials due to make judgments on which consortiums will be given the go-ahead to run the new courses. Successful bids will be announced next month, when the Department for Education and Skills will launch its communications drive, which may involve cinema advertising.
The first pupils will be offered diplomas this autumn. Ministers hope that 50,000 pupils will choose to start diploma courses in 2008, but they have been warned that this may be optimistic.
A source with close links to diploma development said: "The success of the diploma in its first year will depend to a great degree on the choices students make in October and November this year.
"It will be a big step for a student to opt for the diploma straight away, since it will not, at that stage, be live. The advertising campaign will make people aware the diploma is coming."
The source said the name of the new qualification had still to be confirmed. Officials were debating whether to call it a "specialised diploma" or simply the "diploma".
Ministers have billed the qualification as the most important education reform in the world, but teachers are still confused about it.
But Bill Sutton, of the Science, Engineering Mathematics and Manufacturing Technologies Alliance, told a conference last week that the diploma would be the "saviour" of British engineering.