By Paul Carsten and Edwin Chan BEIJING/SAN FRANCISCO (Reuters) – Apple Inc may have to wait a little longer for its watershed moment in China. A disappointing March-quarter revenue forecast, coupled with surprisingly weak holiday iPhone sales, suggest pundits may have over-estimated initial demand from China Mobiles 700 million-plus subscribers, a key factor that has pushed its shares 18 percent higher in the fourth quarter. Apple and China Mobile struck their deal in December, and iPhones went on sale in January. The China Mobile deal, which some analysts expected could boost iPhone sales by as much as 30 million units a year, wont be the knight in shining armor that Apple needs to maintain high growth rates, if its own forecasts are anything to go by.