Not later than October 1, 1987 , each State agency shall develop and submit to the Secretary for approval a plan for the use of an automated data processing and information retrieval system to administer the supplemental nutrition assistance program in such State. The State plan shall take into consideration the model plan developed by the Secretary under paragraph (1) and shall provide time frames for completion of various phases of the State plan. If a State agency already has a sufficient automated data processing and information retrieval system, the State plan may, subject to the Secretary’s approval, reflect the existing State system.