It usually takes about 2-4 weeks for the seed to sprout, given fresh seed and warm temperatures (70-90 deg. F). Thereafter the plant grows slowly for 15-25 years, flowers, and dies. Well before flowering, though, it should have made a number of offsets which will carry on the legacy. Note that all Agaves hybridize promiscuously, so if it was open pollinated seed, the seedlings may not match the mother plant at all!