In any contested probate proceeding in which objections to probate are made and the proponent or the objectant seeks an examination before trial, the items upon which the examination will be held shall be determined by the application of article 31 of CPLR. Except upon the showing of special circumstances, the examination will be confined to a three-year period prior to the date of the propounded instrument and two years thereafter, or to the date of decedent's death, whichever is the shorter period.