TO Causeway Bay for the opening of Times Square, where genial Wharf chairman Peter Woo was not dispirited by the drizzle that threatened to mar the event. When Keeping Posted inquired of Woo why he hadn't done something about the weather, he pointed out with characteristic engaging smile that it wasn't rain but prosperity that was coming down. ''That's a sign of money,'' he quipped. On the subject of moolah, Hongkong Bank chairman John Gray then walked past and, seeing a coterie of his senior executives led by Clint Marshall standing by, inquired with raised eyebrows: ''Who's minding the bank?'' Incidentally, Gray pointed out that he had additional cause to be pleased about the opening of Times Square. His charming wife Ursula's hairdressing salon is situated there. Despite the drizzle, Wharf executive Benny Chan, acting as compere, kept things moving at a brisk pace in the manner of a headmaster conducting assembly at a British boarding school. Taking a keen interest in the proceedings was Swire chairman Peter Sutch. When Keeping Posted gently chided the affable Sutch that this was not a Swire property he responded: ''But we like to come along and support our competitors and see what they are up to.''