In this paper guidelines will be given in order to determine the required measurement time for a specified precision of the Moderator Temperature Coefficient (MTC) estimate by noise analysis. Until now the discussion of the precision of the MTC estimate was neglected. We will study the relation between the precision, the coherence, the amount of temperature sensors and the measurement time. Based on this relation guidelines to determine the optimal measurement time will be given. Simulations in MATLAB will be used to verify the theoretical analysis. Realistic values for the different influencing variables for a specific measurement setup will be given by use of the analysis of a measurement at a Nuclear Power Plant in Belgium.