We report a quantitative analysis of a series of chemically induced convection patterns for the methylene-blue-glucose system at different experimental conditions. The objective of the study is to get some quantitative knowledge of the phenomenon (for example, the characteristic wavelength and the characteristic time for the pattern to appear). We focus our attention on the initial stages of the pattern appearance just after the instability and at some aspects of the general behavior of the complete pattern evolution. We analyze the effect on length and time scales of the patterns obtained when varying the initial values of three different experimental parameters (viscosity, pH, and layer depth). The results obtained in the "linear growth" regime reproduce the qualitative trends extracted from the linear stability analysis of a theoretical model subject to a pseudo-steady-state approximation.