Don't prune in early spring, as many trees bleed sap if cut at this time of year. The exceptions to the 'deciduous tree' rule are maple ... shaped shoots on dwarf and prostrate conifers.
And ‘Shishigashira’ has a dwarf, highly-sculptured look with small leaves ... save heavy pruning of your Japanese maple bonsai tree for late fall or winter. “You could probably do it ...