This study proposes a refined hypothesis on the stepwise emergence of spacetime dimensions from a zero-dimensional (0D) singularity within the Big Bang framework, integrating insights from emergent cosmology, quantum gravity, and stochastic dynamics. Building on prior theoretical developments such as loop quantum gravity and matrix theory, the model posits a sequential dimensional activation: 0D (singularity) → one-dimensional (1D; time, enabling causality) → two-dimensional (2D; light, activating electromagnetic fields) → three-dimensional (3D; space, facilitating cosmic expansion). This phenomenological approach offers a novel pathway toward reconciling quantum mechanics and general relativity, circumventing classical singularities through emergent, temperature-dependent transitions governed by effective Lagrangians and stochastic relaxation. By examining the pre-geometric 0D phase, the 1D temporal scaffold, the 2D wave-like behavior of light, and the full 3D spatial regime, the hypothesis provides a comprehensive framework for early-Universe evolution. Its implications extend to black holes, Big Crunch scenarios, and observational tests via cosmic microwave background (CMB), gravitational wave (GW), and Big Bang nucleosynthesis data, challenging unified 4D spacetime paradigms while aligning with holographic dualities and entanglement-based geometries.