This document discusses metrics for estimating the effort and cost of developing mobile apps. It proposes defining a set of early metrics that can be extracted before full development begins. These early metrics are mapped to guidelines for estimating Cosmic Function Points (CFP). An empirical study evaluates the accuracy of CFP estimations based on the early metrics by comparing them to actual CFP values for 13 mobile apps. The results show the early estimations were reasonably close to the actual values, with mean magnitude relative error of 0.2 and prediction of actual values within 25% for 61% of apps. Future work involves additional validation with companies and gathering more project data.