The stock market could be poised for a 10 percent decline as the Federal Reserve gets ready to hike interest rates for the first time in nine years, BlackRock Global Investment Strategist Russ Koesterich told CNBC on Monday.

"I think there's going to be a better opportunity to buy this market over the next two to three months," he said. "If you look at markets in and around the Fed tightenings, you generally get a 5 percent to 10 percent correction."