Where a time has been fixed for the payment of a general legacy, interest begins to run from the time so fixed. The interest up to such time forms part of the residue of the testator's estate.
     Exception.-- Where the testator was a parent or a more remote ancestor of the legatee, or has put himself in the place of a parent of the legatee and the legatee is a minor, the legacy shall bear interest from the death of the testator, unless a specific sum is given by the will for maintenance, or unless the will contains a direction to the contrary.