Isso pode funcionar apenas
@echo off
set looptime=30
set /a "T1=(%time:~6,2% + %looptime% ) %% 60"
:loop
Echo %Random%%Random%%Random%%Random%%Random%%Random%%Random%%Random%%Random%%Random%%Random%%Random%%
set T2=%time:~6,2%
if not %T1% == %T2% goto loop
:: continue with whatever