Like Joseph said, the real issue hinges on whether there is any legitimate basis to derive 2520 years from the "seven times" of Daniel. This is a form of typological interpretation totally without Scriptural precedent or support. What relatively little typology may be detected in the NT is "thoroughly christological in its focus" (New Testament Interpretation, p. 210-2). Neither covenant typology, nor creation typology, nor synthetic typology, nor antithetic typology, nor judgement typology can be hermeneutically stretched from the 6th century BC to the 20th century AD to "jump over" Christ.
Craig