The existence of luminous quasars hosting supermassive black holes (SMBHs) within the first billion years of cosmic history challenges our understanding of black hole growth. An important piece to the puzzle is the duty cycle of quasars, the fraction of cosmic time that galaxies shine as active quasars and during which the bulk of the black hole growth occurs. I will present two new avenues towards understanding the early growth phases of SMBHs: Firstly, I will show a novel method to constrain the timescales of quasar activity using the extent of the ionized regions around quasars, and, secondly, I will present the first quasar clustering measurement at z>6 using recent observations from the James Webb Space Telescope that allow us to estimate the quasars' host dark matter halo mass and their duty cycle. We find that SMBHs seem to grow on much shorter timescales than expected, providing a potential solution to the long-standing puzzle of early black hole growth. I will show how we aim to understand the dominant processes that govern black hole growth using a combination of multi-wavelength observations and data-driven models.