  The optimization of the mixing of a passive scalar at finite P\'eclet number
$Pe=Uh/\kappa$ (where $U,h$ are characteristic velocity and length scales and
$\kappa$ is the scalar diffusivity) is relevant to many significant flow
challenges across science and engineering. While much work has focused on
identifying flow structures conducive to mixing for flows with various values
of $Pe$, there has been relatively little attention paid to how the underlying
structure of initial scalar distribution affects the mixing achieved. In this
study we focus on two problems of interest investigating this issue. Our
methods employ a nonlinear direct-adjoint looping (DAL) method to compute fluid
velocity fields which optimize a multiscale norm (representing the `mixedness'
of our scalar) at a finite target time. First, we investigate how the structure
of optimal initial velocity perturbations and the subsequent mixing changes
between initially rectilinear `stripes' of scalar and disc-like `drops'. We
find that the ensuing stirring of the initial velocity perturbations varies
considerably depending on the geometry of the initial scalar distribution.
  Secondly, we examine the case of lattices of multiple initial `drops' of
scalar and investigate how the structure of optimal perturbations varies with
appropriately scaled P\'eclet number defined in terms of the drop scale rather
than the domain scale. We find that the characteristic structure of the optimal
initial velocity perturbation we observe for a single drop is upheld as the
number of drops and $Pe$ increase. However, the characteristic vortex structure
{\color{red} and associated mixing exhibits some nonlocal variability,}
suggesting that rescaling to a local $Pe$ {\color{red} will} not capture all
the significant flow dynamics.
