CNBC's Fed Survey this week showed that expectations are now that the Fed will begin to move away from its $85 billion in monthly bond and mortgage purchases in February—two months earlier than expected in an October survey of fund managers and others. Fifty-five percent see the Fed tapering in January or December, while more than 40 percent expect it in March or later.
(Read more: The Fed will never end QE: Marc 'Dr. Doom' Faber)
Bernanke's successor, Fed Vice Chair Janet Yellen, is expected to be approved shortly, and this could be the final meeting presided over by Bernanke, who guided the Fed through the financial crisis and headed the implementation of its extraordinary policies. His term officially ends after the January meeting.
Stone said that if there is a move to taper its bond-buying Wednesday afternoon, the stock market would sell off, but less than 1 percent. If the Fed does nothing, stocks could rally about the same percentage. Treasurys were higher Tuesday, helped by a strong 2-year auction. The yield on the 10-year slipped to 2.839 percent, and bond strategists say it would head toward 3 percent if tapering were announced.
"It may give us greater odds for a Santa rally if they don't taper," Stone said. The rally is named for the trading days right after Christmas and the first few days in January, when market bias is often higher.
But the markets are not primed for tapering just yet, according to Pimco portfolio manager Tony Crescenzi.
"Tomorrow wouldn't be the best timing for taper because the market isn't expecting it," he said. "It was OK to surprise the markets with a positive one in September, but it's not as OK to surprise the market with one that is somewhat more negative, unless the Fed finds a potent mix of goodies to help soften the blow."
Crescenzi said that the Fed could reduce the interest paid on excess reserves but that it is not likely. It may also attempt to guide markets to expect low short-term rates for longer by cutting the 6.5 percent unemployment it set as the level at which it would begin to raise short-term rates.
The unemployment rate is 7 percent.
"The Fed is trying to pivot from a bond buying to a communications strategy," he said.
(Read more: Fed-inflated stocks a 'hall of mirrors': Jim Grant)
"The reason tomorrow feels somewhat ill-timed is because the Fed already had one communications mishap this year," Crescenzi said. Markets were surprised when it held back from tapering in September because of concerns that fiscal restraints were hurting the economy.
But Ward McCarthy, chief financial economist at Jefferies, said the Fed has already readied the runway and needs to act to pare back bond-buying.
"I think the statement language will indicate they are reducing the purchases by $5 billion but would implement the reduction in Treasurys," he said. The Fed is currently purchasing $45 billion in Treasurys and $40 billion in mortgage securities each month.
The initial slowing of bond-buying is actually still a long ways from removing stimulus. Besides its QE purchases, the Fed actively replaces securities on its balance sheet as they mature, and it has no plans to unwind the giant holdings on its balance sheet.