Stocks drifted mostly higher in subdued trading yesterday as Wall Street tried out its early opening schedule and mopped up orders left over from Friday, when Hurricane Gloria closed the exchanges.

The Dow Jones industrial average closed up 7.84 points at 1,327.63, with much of the gain provided by General Foods, one of the components of the 30-stock average. General Foods, which said Friday it would be acquired by Philip Morris for $120 a share, rose 7 7/8 to 118 3/8. Philip Morris was down 5/8 at 75.

Volume on the New York Stock Exchange was 103.62 million shares.

The market ended its September trading yesterday with the Dow Jones industrials chalking up a net loss for the month of 5.38 points and a third-quarter decline of 6.83 points.

As forecast, the change in the opening hour of the NYSE to 9:30 a.m. from the traditional 10 a.m. start left the retail brokerage community cold -- especially in California, where brokers keep New York hours and now must begin trading at 6:30 a.m.

Martin P. Albanese, the chief of Prudential-Bache's NYSE floor operation, said that, when the market opened yesterday, he noticed an increase in the number of orders arriving from the firm's London office. He said they were chiefly buy orders from London institutions for U.S. blue chips and probably would have come in anyway.

However, Albanese said he expected an increase in business from Europe because the 9:30 a.m. start gives the NYSE a one-hour overlap with trading on the London exchange -- giving traders there more time to manuever. "The longer period of live trading is an advantage," Albanese said.

A trader at a Wall Street firm, who spoke on condition that he not be identified, said that the extra time would help major U.S. firms with offices in London reduce the amount of third-market, or off-the-board, trading they do to accommodate European clients. He said that the U.S. firms prefer to trade on the NYSE floor, because it reduces their risks and costs.

At the NYSE, 16.3 million shares were traded from 9:30 a.m. to 10 a.m. and another 20.7 million shares from 10 a.m. to 11 a.m., for a total of 37 million. On the previous Monday, when the market rose by more than 18 points because of international action on the dollar, a total of 36.2 million shares were traded by 11 a.m. A week earlier, only 18.5 million shares were traded by 11 a.m.

On the American Stock Exchange, 1.2 million shares changed hands from 9:30 a.m. to 10 a.m. and another 1.1. million from 10 a.m. to 11 a.m., for a total of 2.3 million. The previous Monday, the day of the 18-point climb, 2.4 million shares were traded by 11 a.m., but only 1.4 million moved in that time period a week earlier.

Some market observers said they believe that it will take time for an early-morning trading pattern to emerge.

Washington area brokers said they did not expect, or see, any early rush to trade. John Lanza, manager of the Quick & Reilly office, said "most people just weren't aware" of the earlier trading time. Carole Rollinson, manager of the Prudential-Bache office in Bethesda, said there was "hardly any" early-morning business. And Leslie J. Silverstone, head of a Dean Witter downtown office, said that "so far, it's a nonevent."

On the West Coast, Rick Dirickson, managing director for retail sales at Hambrecht & Quist, said "if you're asking, 'Did we get a surge of calls?' the answer is categorically no." William T. Dailey Jr., director of sales for Montgomery Securities, which deals chiefly with institutions, said that the extra 30 minutes would have no meaning to institutional buyers.

The Pacific Stock Exchange reported no appreciable change in trading in either stocks or options. From the standpoint of people who have to get to work by 5:30 a.m. to get ready for 6:30 a.m. trading, the new schedule is a "real psychological minus," said Ron Sallerson, the PSE's options marketing manager.

In other Wall Street action involving takeover stocks, Richardson-Vicks led the active list and gained 10 to 63 1/2. Unilever U.S. Inc. said a federal judge had issued a preliminary injunction restraining Richardson-Vicks from issuing a new preferred stock proposed in response to Unilever's bid to acquire the company. Brokers also said there was speculation that a higher offer for the company might be forthcoming.

Meanwhile, Pacific Lumber gained 6 to 39 on word that Maxxam Group plans a bid for the company.

The daily tally on the Big Board showed advances slightly outnumbering declines. The exchange's composite index of more than 1,500 common stocks rose 0.37 point to 105.19.

Nationwide turnover in NYSE-listed issues, including trades in those stocks on regional exchanges and in the over-the-counter market, totaled 126.73 million shares.

Standard & Poor's index of 400 industrials gained 0.98 point to 203.67, and S&P's 500-stock composite index was up 0.78 point at 182.08.