The Dublin Region Homeless Executive has admitted that not all homeless families may be out of hotel accommodation by the 1 July deadline.
The commitment to end emergency hotel accommodation was made by Housing Minister Simon Coveney TD as part of the Rebuilding Ireland plan.
A department spokesman said that the Government is still working towards that target but admitted it is "ambitious".
There are 695 homeless families being put up in hotels according to the latest official figures.
The Dublin Region Homeless Executive says that work on 18 sites for 'family hubs' is continuing and should accommodate 634 families by the end of June or early July - half of these will be converted hotels.
But they will provide families with their own laundry and cooking facilities as well as a range of support services.
The homeless executive said that the remaining families could be accommodated under the Housing Assistance Payments (HAP) scheme which supports tenants in the private sector.
Another 39 "rapid-build" houses are due to be ready in Finglas during July after a series of delays in the programme.
At present there are only 22 such homes completed, which are all in Poppintree, Ballymun.
Focus Ireland has criticised the use of family hubs which cater for up to 50 families at a time.
Mike Allen the charity's director of advocacy said the experience in other countries was that families in this type of accommodation ended up with deeper problems.
Sinn Féin Cllr Daithi Doolan, chair of Dublin City Council's Housing Committee, said Minister Coveney should concentrate on building social housing and protecting people in private tenancies rather than "going after the headlines".
Eileen Gleeson, director of the homeless executive, said the family hubs are a temporary measure until permanent accommodation is found.
She said the biggest problem is the continuing numbers of families becoming homeless with 60 to 70 new families presenting every month.
