Parents will be invited to apply for the Pounds 1,100 vouchers in January with the first redeemed in April - possibly just a month before the general election.
More than 14,000 four-year-olds living in the four pilot local authorities - Norfolk, Westminster, Wandsworth and Kensington and Chelsea - have vouchers. When the scheme goes national next year 650,000 children are expected to be eligible for them.
Civil servants acknowledge that the biggest difficulty will be persuading parents of children already in reception classes that they will need a voucher.
They are proposing now to spend Pounds 850,000 on TV and radio advertising for the scheme. An extra Pounds 475,000 is being spent on posters and leaflets and Pounds 50,000 on newspaper adverts.
All parents will be urged to take up the vouchers. In the pilots, 91 per cent of the estimated number of eligible parents applied for vouchers. In Wandsworth the figure was 96 per cent, and in Norfolk 97 per cent.
Officials in Norfolk said there were just four youngsters they had not been able to trace - the children of travellers.
The Department for Education and Employment has now been liaising with travellers education groups to ensure that travellers' children get their vouchers. If they move during the term they will have to apply for vouchers for their new schools.
The children of service families will be eligible even if their parents are working abroad.
Overseas students who bring their children to the UK while they study will have to provide evidence of the child's age and existence either through birth certificate or other Government documentation for them to qualify.
As in the pilot scheme, heads will be able to use "school-issued application forms" where the parent is unable or unwilling to apply for a voucher. There will be no limit on the number issued per school and they need only to be signed by the head, not the parent.
Civil servants are planning to issue vouchers during the previous term to which they relate to give schools the chance to collect early. They are also going to simplify administration arrangements and reduce the amount of form-filling by doing away with the requirement in the pilot that every school fill in a form giving a child's name.
When the scheme goes national schools will only have to enter a number of children eligible and using vouchers.
It will be up to local authorities to decide whether they want to collect the vouchers themselves - and civil servants have suggested it may be a good way of keeping tabs on the scheme - but the DFEE has insisted: no voucher, no payment.
DFEE timetable of events
* October - invitation to providers (schools, private sector, voluntary sector) to join the scheme. Pounds 1.3m advertising campaign aimed at parents of all children who will be eligible in April 1997.
* December - deadline for providers to register to be included on the list sent to parents. z January - application form to parents including list of providers.
Office for Standards in Education report on first inspections.
* February - vouchers issued.
* March - School Curriculum and Assessment Authority suggestions for four-year-olds.
* April - vouchers redeemed.