When Ben Bernanke and other members of the Federal Open Market Committee meet next week, the tough decision won’t be what to do about current monetary policy; it will be what to do with two words: extended period.

That’s the phrase the Fed has used to describe how long it will keep interest rates in the band of zero to 0.25 percent since March, when it also announced the extraordinary measure of buying $300 billion of U.S. Treasuries to get credit markets and the economy moving again.

The purchase program officially ends Friday, and its larger program to bolster the mortgage market should end early next year.

Tweaking the language describing how long the Fed expects to keep rates so low next week would therefore be the logical next step. The Financial Times reported last week that senior officials were in fact considering such a change. They just shouldn’t do it next week.

These incredibly nuanced shifts in language, like changing “extended period” to say “for some time,” became the Alan Greenspan Fed’s preferred way to communicate the steady march toward eventually tightening policy before the Fed pulled the trigger in June 2004. “Considerable period” in 2003 gave way to “patient” in January and “measured” in May.

Prepping the market is a good idea, but only when there’s evidence that the economy can withstand more expensive financing. Market rates that influence everything from home mortgages and corporate borrowing costs begin to rise well before the Fed eventually starts tightening policy. In the year that Greenspan held rates steady at 1 percent, for example, the two-year Treasury yield rose more than 1 percentage point as the policy hints evolved.

But the state of the job market alone is reason to forget about nuance for the moment. In September, the unemployment rate reached 9.8 percent — its highest point in more than two decades. Many expect it to climb above 10 percent before it peaks. In the last downturn, unemployment reached a nadir of 6.3 percent in the month that the Fed stopped tightening. The language shifts came about only as employment began to improve.

This should keep a cap on calls for higher wages for some time to come, which in turn means the Fed won’t have to worry too much about inflation. Indeed, the government reported today that worker compensation grew only 1.5 percent in the year through September, almost half the increase seen in the prior 12-month period.

This isn’t to understate the dangers of keeping policy too easy for too long. After all, Greenspan’s reluctance to derail an economic recovery helped inflate the housing bubble. But let’s at least wait until the job market steadies before readying for a change.