If you've been postponing a decision on financing a new home or refinancing your present house to catch a favorable point in the interest-rate cycle, don't put off your decision too much longer.

The three-month downward flutter of home-loan rates -- particularly the short-term adjustables -- shows signs of having run its course. Short-term interest rates in the economy as a whole still may edge lower by a notch or two, but mortgage rates probably won't follow suit. Quotes nationwide have stabilized in the past week and are more likely to inch back upward in the coming 12 weeks than they are to fall significantly.

That's what's in the crystal ball, at least, of the man who runs the nation's largest and most influential home mortgage financial firm. Economist Mark J. Riedy, president and chief operating officer of the $90-billion-asset Federal National Mortgage Association (Fannie Mae), sees no dramatic movements -- upward or downward -- anywhere in sight for three months.

Nor does he recommend that anyone rush to sign up for a new home this spring solely on interest-rate grounds. The gradations from week to week aren't likely to be so sharp as to be the critical factor in a go or no-go decision on a home.

What Riedy does suggest, however, is that mortgage money costs well may be at or near their "psychological low point" for the current cycle. He points to two key indices:

*The movers and shakers in the national capital market -- particularly on Wall Street and at the Federal Reserve Board -- are split over whether the economy is growing too sluggishly or too quickly. Three months ago, by contrast, there was general agreement that the economy needed a solid shot of medicine, which the Federal Reserve supplied by loosening its credit strings. That's where the lower rates came from.

Today's uncertainty about growth, in short, augurs for a flattening of rates, instead of further easing.

*Mortgage market lenders are beginning to wonder aloud about how low rates should go. Riedy expresses concern that the current single-digit quotes on one-year adjustable-rate mortgages "may tend to bring in some home buyers who will prove to be only marginally qualified" -- and therefore greater credit risks. (Fannie Mae's quote for its popular one-year adjustable stood at 9 percent on June 19, exclusive of servicing fees and loan origination charges.)

Lenders offering fixed-rate mortgages in the 12 1/4 to 12 1/2 percent range "have to ask themselves how much lower they want their yields returns to go for the time being," in Riedy's view.

With loan demand for housing strong, in other words, many fixed-rate lenders may now want to hedge their bets against future inflation, and stop the current cycle where it is, rather than go lower. What does Riedy's perspective offer in practical terms for home buyers or owners who are planning to plunge into the mortgage-financing marketplace?

First, don't hold your breath for significantly better rates any time soon. The crop of adjustable, fixed-rate and so-called convertible loans available nationwide this spring is better-priced and more varied than any in the past four years.

One- and three-year adjustables, for instance, offer cost-effective options to homeowners seeking to pull money out of their real estate via refinancing. If you believe -- as Riedy and a number of other economists do -- that rates are not likely to rise dramatically in the coming year or two, adjustables at 10 to 11 percent provide the lowest-cost home mortgage dollars in the market today with relatively modest risk.

If your adjustable comes with the increasingly popular convertibility option (allowing you to switch to a permanent 30-year, fixed-rate loan at set intervals during the course of the loan term), you can hedge your refinancing bet even further.

Fifteen-year, fixed-rate loans should represent still another well-priced alternative this month and next. Most lenders offer them at one-half a percentage point or greater discounts from 30-year fixed rates. Fannie Mae's quotes, for example, were at 11 percent last week versus 11 1/2 percent for 30-year fixed (plus servicing fees).

If Riedy is right, fixed rates won't be much better than that for the foreseeable future. It could be the right moment to lock up the loan money you need.