plotting – Date ticks with SmoothHistogram3D

Try this:

SmoothHistogram3D[data,
 Ticks -> {
   {#, DateString[#, {"Day", "/", "Month", "/", "YearShort", " ", "Hour24Short", ":", "MinuteShort"}]} & /@ 
    FindDivisions[MinMax@data[[All, 1]], 5],
   Automatic,
   Automatic}
]

with dates and times as ticks

Look at the documentation of DateString to see how to customize the date string specification to your needs.