A key step towards a better understanding of nucleon structure in terms of generalized parton distributions (GPDs) is the measurement of Deeply Virtual Compton Scattering off the neutron (nDVCS; $ed\to e'n'\gamma(p)$). This process allows access to the GPD $E$ of the neutron, which is one of the least constrained GPDs.The determination of $E$, together with $H$ for both the proton and the neutron, can provide information on the quark total angular momentum - via the Ji's sum rule - conveying a more complete picture of nucleon structure. The GPD $E$ is accessed in nDVCS through a Beam Spin Asymmetry (BSA) observable. The measurement of the BSA of nDVCS, combined with observables from pDVCS measurements, allows us to perform the flavor separation of relevant quark GPDs via linear combinations of proton and neutron GPDs. Here, we provide details on the data analysis along with preliminary BSA for nDVCS extracted with the experiment recently carried out at Jefferson Lab using the upgraded CEBAF 11 GeV polarized electron beam and the Hall-B CLAS12 detector.