Estimated times are just that -- estimated. I agree on both points that the seed banks estimate from the start of flowering and that they tend to be based on the most optimum of conditions. Mine tend to run a little longer for the most part. That said, you are at a point where time does not matter. Do what you are doing... Check the trichomes daily and when they turn milky white, not clear, they are ready. Since you are growing different strains they will most likely finish at different times. And, yes, to the question of Sativa's taking longer -- up to month or more depending on the strain and conditions. Both of yours, however, are Indica dominant.