I think I just found an answer but I leave open the question for the sake of the community:
Actually using the theorem found here (1) :
$$CXC^t \sim W(n,C\Sigma C^t)
$$
and taking $C$ as the diagonal matrix :
$$\left( \begin{matrix}
\sqrt{c} & \ldots & 0 \\
\vdots & \ddots & \vdots \\
0 & \cdots & \sqrt{c} \\
\end{matrix} \right)
$$
Ergo in this case $cX$ should be $W(n,c\Sigma)$ distributed and then, for. Relating to my example for the covariance sample purpose should becovariance, $\frac{1}{\sqrt{n}}$$C = \text{diag}(\frac{1}{\sqrt{n}})$. In this wayHence, $\frac{1}{n}X=\hat{\Sigma}$ should be simply $W(n, \frac{1}{n}\Sigma) $ distributed.