Parents want full-day attendance after the first weeks but teachers insist younger children need time to settle, despite the norm of two years' nursery that is meant to prepare them for school.
The council surveyed headteachers, teachers, school boards and parents on the infants' day after concerns that teaching time was being lost. Different schools have different policies.
John Christie, director of education, said standard practice had been to phase primary 1 entry by running half-day attendance up to the October holiday. Pupils then worked a longer day but still not a full day. However,a significant number of schools ask first-year pupils to attend for the full five hours.
The survey revealed overwhelming support for P1 pupils to attend for a half day until October but a clear majority of parents felt they should not have a shorter day throughout the session. Arranging transport is a problem, especially if they have other children at primary, they say.
Heads argued firmly for half-day attendance to October and a shorter day throughout the session. Parents and teachers agreed children in P2 and P3 should attend full-time.
Councillors on Tuesday agreed to set a common policy of half days until October followed by a reduced school day of four and a half hours.