Make a relay loop that loops X times, each loop lasting 30 seconds, before executing the wanted event.
Example:
0 onTrigger -> self -> setvariable [counter] [10]
33 onTrigger -> self -> fireRelay
0 onRelay -> self -> ifvariable [counter] > 0
0 onVariableTrue -> self -> modVariable [counter] -> substract 1
30000 onVariableTrue -> self -> fireRelay
0 onVariableFalse -> ....
The syntax isn't right, but you get the point. It's basically a while-loop.