There they are, the harbingers of Mother's Day, 1982:

An article in the paper warning about the problems of teen-age mothers. An ad for a television program warning about the problems of older mothers. A magazine piece warning about the problems of mothers in their twenties who try to raise a baby and a career together.

Sifting through these charming seasonal gifts of media mothering, I decided that the only years left uncovered by dire warners were the magical years between 1 and 10, and the wonder years between 60 and 90. But I also understood, finally, why the most common question about mother these days is not "why" or "whether" but "when."

Not long ago, young women on college campuses would stop visitors from the real world with an anxious inquiry: Can you balance career and family? Today the same people with the same anxiety are asking: What is the best time to have a baby?

The old issue, "juggling," has a new twist, "timing." The balance of work and children now hinges on the sequence.

There is a notion that if a woman can pinpoint and plan the "best time" to become a mother, then everything else will fall into place. If the key words in real estate are location, location, location, now the key words in mothering are timing, timing, timing.

Frankly, I have always been intrigued with the age gaps between mothers and children. Of my two closest friends, one is five years older than I and the other is five years younger. But among us, we have children who range from 25 years to four weeks old. The oldest girl has her own apartment, the youngest her own crib.

We are a walking sample of decisions. One of us had children first and career second. The next nurtured both from infancy, like twins. The youngest established her career first and had her children second.

There is no doubt in my mind that the planning and non-planning, the spacing and timing of our children made enormous differences in our lives. We were and are and will be different ages at our children's different ages.

So, the three of us share certain experiences in the time-study business. We know with certainty that a girl of 15 or 18 needs to have a mother and not be one. Beyond that we know about tradeoffs. A new mother at 25 has more energy and less self-confidence. A new mother at 35 has a stronger identity and a weaker back. A mother who gives birth at 27 has more freedom at 45; a mother who gives birth at 35 had it at 27.

But if asked to arrive at a consensus in the planning motherhood business we would all offer the practical, safe advice of the 1980s: start a career first, a family second.

Yet, at the approach of this Mother's Day, I confess to certain qualms. Not about whether the advice is good, but about why it's good. I wonder if too many women are trying to "fit" children into their lives at a convenient moment. Convenient for the work force, convenient for the status quo.

I admire their determination to follow a sensible life plan. Yet I wonder if this determination doesn't prevent them from rewriting the plan.

It makes sense for a woman in business to become a manager before she becomes a mother. It makes sense for a woman who is training to be a doctor to postpone a family until she finishes residency. It makes sense to become established before you become pregnant. Yet maybe this sense is a setup.

In the ongoing tension between family and work, we are constantly devising private solutions instead of revising the public ones. We work within the requirements of a make-it-or- break-it marketplace, instead of challenging them. Too often we end up forced to fit our families in and around the pieces set in place by work.

Does our adjustment now begin at conception? Is this a sign of our flexibility or the working world's rigidity? Is it our free choice or their choices? Is it our family planning or theirs?

I don't, I'm sorry to say, have a perfect alternative maternal schedule to propose for this Mother's Day. There are solid reasons to plan around the workalogical clock. Yet once a year, those of us who are already mothers should tip our hats to the truth. Ultimately children don't fit into a schedule. They expand it, complicate it, enrich it.

In the motherhood business, time is still more crucial than timing, timing, timing.