For working couples, weddings require careful planning

In a pale pink-walled dressing room at Priscilla's bridal shop here, a young woman on her lunch hour is trying on a graceful ivory gown. ''I'm not sure about the veil,'' she says to the assistants, carefully eyeing the waist-length cascade of net in the full-length mirror.

Like this professional, most working women about to be married must snatch time when they can to plan for their weddings. Many do not have the luxury of mothers or relatives living close by to help order flowers, scout out reception locations, find musicians and caterers, or assist with the myriad of other details involved in planning the event.

''You count the number of Saturdays from the time of your engagement to your wedding day and that's about all the time you have,'' says one newlywed.

According to spokesmen in the wedding industry, many professional women approach the wedding market with an eye for practicality as well as romance.

''A working woman has a definite advantage because she knows how to ask the right questions,'' says Barbara D. Tober, editor of Bride's Magazine. Chances are ''she knows how to be a good consumer, and buying wedding services is no different than buying anything else. She's savvy about what she should be getting for her money.''

According to the research department of Bride's Magazine, today's average bride and groom are older and more affluent than a decade ago. About 20 percent of all women getting married for the first time are over 25. About one-third of those are in their 30s or older.

In many cases, Bride's Magazine reports, these women and their fiances have worked for a few years and are picking up all or part of the tab for their weddings.

Grooms are also playing a larger role in the planning. Couples who already have well-stocked kitchens and linen closets may register for gifts at gourmet food shops, luggage shops, or bookstores rather than jewelry or department stores.

''They've gone to college, they've worked, they've traveled, and they've picked up friends along the way,'' Ms. Tober says. Weddings drawing friends and family members from many locations often result in a series of weekend events. ''Very often if it's going to be a big occasion, other family celebrations such as a birthday or an anniversary are attached to the wedding,'' she notes.

After deciding on locations for the ceremony and reception, picking out a wedding dress is usually one of the first items on a bride's agenda.

''Professional women are more inclined to be independent in their choices. They are not being directed by a relative such as their mother,'' says Betsy Kidder, director of advertising and public relations for Priscilla - the Bride's Shop Inc. Some of these women also pay for their own gowns, she notes.

''It used to be a phenomenon to see any man other than a father here, and that was a rarity,'' says Fran Barrette, manager and buyer at Priscilla's. ''Now quite a few brides bring their fiances with them rather than their mothers.''

While some older brides opt for the traditional wedding dress complete with train and veil, ankle-length or ''tea length'' gowns are popular choices. One such style shown at Priscilla's is an ankle-length French-lace dress worn with a lace jacket and white or pastel-colored slip. The slip can be interchanged for another color and worn on another occasion.

''She can look like a bride the day of her wedding and use the dress afterward,'' says Mrs. Barrette.

Even the most organized couples find planning for a wedding can have its share of snags.

Pam Willoughby, who married her husband, Todd, in March, describes her first day shopping for a wedding dress as ''one of the most discouraging days I ever went through. I must have tried on 40 dresses - they were all so extreme. Then I went to a little place recommended by a friend and I chose the first dress I tried on.''

The Willoughbys, who both work, started planning their wedding about six months in advance.

''We needed every second of it,'' says Mrs. Willoughby, a buyer at Bullock's department store in Los Angeles. ''We had a lot of input from different sources. We spent a lot of time really listening to ideas.''

Once the couple decided on the type of ceremony and reception they wanted, they delegated tasks to family members who carried out the details.

''Lists were essential,'' says Mrs. Willoughby, who is in her mid-twenties. She recommends involving family members as much as possible. ''It makes the planning go more smoothly - it gets more people involved. When everyone has their input, everyone's pleased with the result.''

Some working women enlist the services of bridal consultants in department stores or in the community to help orchestrate their wedding. Others find they need to curtail working hours before the event.

''One of the things I decided I needed to do was to work part time a month before the wedding,'' says one 28-year-old Boston professional who will be married this month. She started planning the wedding about six months in advance with some help from her fiance.

''The big thing was setting a budget, since we're paying for it all on our own. We had to decide whether the party or the ceremony would be the important part,'' she says. Her husband-to-be has five children from a previous marriage, and ''it was important to keep the children involved in the planning so they always feel included.''

A large part of the preparations included looking for and purchasing a new family home. Her fiance's two oldest daughters also have attended bridal showers , helped choose furnishings for their new home, and will assist at the reception. His two sons will be ushers.

''At first I didn't want a big wedding,'' she says, ''but you do it once and you want it to be special.''