The earliest stage of relativistic heavy-ion collisions is predicted by the Color Glass Condensate (CGC) effective theory to be a classical state called Glasma. The evolution of the Glasma is described by the classical Yang-Mills (YM) equations, but there is no analytic solution to these equations for the full collision problem. I show how we linearize and solve the YM equations using the dilute approximation. Extending previous work [1], we express the 3+1D (rapidity dependent) field-strength tensor of the Glasma as a three-dimensional integral. This gives a description of the nontrivial rapidity structure of the Glasma energy-momentum tensor. Finally, I discuss different 3D nuclear models within our framework. [1] A. Ipp, D. Müller, S. Schlichting and P. Singh, Phys.Rev.D 104 (2021) 11, 114040 [arXiv:2109.05028]