The IBM Systems Division has begun to move into the first building of the Rockledge Executive Plaza being developed on a nine-acre tract north of Democracy Boulevard in Montgomery County.

All of the 168,000 square feet in the first building is being occupied by the IBM Systems Division. A second six-story building, where construction already is under way, has been preleased to Suburban Bancorporation, and some of that space has been subleased.

Spaulding & Slye Corp., based in Boston and with an office in Rockville, is developing and managing the buildings, designed by Donald N. Coupard & Associates. New England Mutual Life Insurance Co. is a partner in the joint venture.

The contemporary "sister" buildings are located near the headquarters of Martin Marietta and Marriott. IBM also has a data-processing building nearby. The total industrial park site is located east of Montgomery Mall and is bounded by two legs of I-270, Democracy Boulevard and Old Georgetown Road.

Elsewhere and otherwise:

Industrial Realtors across the land are expecting an upturn in sales and leasing, according to a survey made by the National Association of Realtors. lAfter a period of generally lukewarm activity, 45 percent of responding industrial specialists were optimistic about an upturn later this year.A year ago only 29 percent were optimistic. However, areas with an acknowledged oversupply of industrial space increased from 13 percent last spring to 36 percent this spring.

Construction at the Jermantown Square office-retail center at Lee Highway and Jermantown Road in Fairfax County is nearly completed. The Bacas Co. is leasing agent for the colonially styled center scheduled to be open in July.

The Washington Board of Realtors, which has been located in the Investment Building for more than 20 years, is facing a lease-renewal decision. The WBR is considering moving into space that will be available in the Wyatt Building, which now is owned by the National Association of Realtors. Or the WBR may relocate in a small landmark-type building that it may purchase and renovate on Capitol Hill. The WBR executive board has not yet reached a decision.

The National Association of Industrial and Office Parks has scheduled a morning seminar on Friday at the Springfield Hilton. The topic: valuation of income-producing properties. For information, call (703) 836-1300.

"A Guide to Commercial Management," described as the complete operating manual of the Charles E. Smith Cos., has been published by the Building Owners and Managers Association. The 338-page book, written by Smith executive vice president, Sidney Glassman, is available for $24.95 (plus $2.25 postage) from BOMA, 1221 Massachusetts Ave. NW, Washington, D.C. 20005.

James F. Coakley of Alexandria has joined Leggatt McCall & Werner Co. here as an office leasing specialist.