At the luminosity of 2 (.) 10(33) cm(-2) s(-1) foreseen for the initial period of operation, about 10(6)b (b) over bar pairs are expected to be produced per second at LHC. With these huge statistics a detailed study of many issues of B Physics, such as CP Violation, B-s oscillations and rare decays can be performed. The performance of the precise CMS tracking detector within the requirements of the initial CMS DAQ setup in the selection at trigger level of some specific benchmark B decay channels is presented, and the possible CMS physics reach for these channels is discussed.