  We study how the kinetic decoupling of dark matter (DM) within a minimal
supersymmetric extension of the standard model, by adopting nine independent
parameters (MSSM-9), could improve our knowledge of the properties of the DM
protohalos. We show that the most probable neutralino mass regions, which
satisfy the relic density and the Higgs mass contraints, are those with the
lightest supersymmetric neutralino mass around 1 TeV and 3 TeV, corresponding
to Higgsino-like and Wino-like neutralino, respectively. The kinetic decoupling
temperature in the MSSM-9 scenario leads to a most probable protohalo mass in a
range of $M_{\mathrm{ph}}\sim 10^{-12}-10^{-7}\,M_\odot$. The part of the
region closer to 2 TeV gives also important contributions from the
neutralino-stau co-annihilation, reducing the effective annihilation rate in
the early Universe. We also study how the size of the smallest DM substructures
correlates to experimental signatures, such as the spin-dependent and
spin-independent scattering cross sections, relevant for direct detection of
DM. Improvements on the spin-independent sensitivity might reduce the most
probable range of the protohalo mass between $\sim$10$^{-9}\,M_\odot$ and
$\sim$10$^{-7}\,M_\odot$, while the expected spin-dependent sensitivity
provides weaker constraints. We show how the boost of the luminosity due to DM
annihilation increases, depending on the protohalo mass. In the Higgsino case,
the protohalo mass is lower than the canonical value often used in the
literature ($\sim$10$^{-6}\,M_\odot$), while $\langle\sigma v\rangle$ does not
deviate from $\langle\sigma v\rangle\sim 10^{-26}$ cm$^3$ s$^{-1}$; there is no
significant enhancement of the luminosity. On the contrary, in the Wino case,
the protohalo mass is even lighter, and $\langle\sigma v\rangle$ is two orders
of magnitude larger; as its consequence, we see a substantial enhancement of
the luminosity.
