See QMC->Source Documents->Select document->Task->Reload->Script Parameters. Enter a variable name in the top input box and a value that controls which QVDs will be stored by your document in the lower one.
Note that the variable must exist before script execution is started. Create the variable in the Variable overview instead of in your script. If you manipulate your variable in your script with LET/SET v=value, then you'll always loose the passed value.
QMC Help contains more information on how to set this up and how to pass multiple values (for example to create multiple end-user documents)
What I will do in this case is to split my script into 2 part using variable (i.e. vReloadTime) See below for example. Still pass the variable into QMC i.e. QMC->Source Documents->Select document->Task->Reload->Script Parameters.
Set up two task 8:00 AM and 9:00 AM using same qvw file.
Goto QMC, select Documents tab -> Source Documents tab then click on the + sign to navigate to the qvw file you want to split the task. Then click on the Edit Task button (it's Pencil like shape) the select Reload tab. Here you will find where you can enter Parameter Name and Parameter Value