Based on the ".ps1" (Windows PowerShell script) example above, I've written a regular ".bat" script file to change the clock time at which the VirtualBox's virtual machine starts.
The desired start time is set at variable "TEMPO_START_TIMESTAMP" in epoch format. You can get your desired start time epoh equivalent at "http://www.timestampconvert.com/".
The name of the VirtualBox's virtual machine to be started is needed in variable "NOME" (same nomenchature used in the ".ps1" script above).
echo off
echo %time%
set NOME="Windows_7_x64"
set TEMPO_CS_2_MS=0
set TEMPO_S_2_MS=000
rem # Starts the VM always on the date 07/11/2014 - 11h58
rem http://www.timestampconvert.com/
set TEMPO_START_TIMESTAMP=1415361480
for /f "delims=" %%x in ('cscript /nologo toEpoch.vbs') do set epoch=%%x
rem %epoch%
set TEMPO_CURRENT_TIMESTAMP=%epoch%
rem set TEMPO_CURRENT_TIMESTAMP=1544518714
set /A TEMPO_TEMP=(%TEMPO_START_TIMESTAMP%-%TEMPO_CURRENT_TIMESTAMP%)
call set TEMPO=%TEMPO_TEMP%%TEMPO_S_2_MS%
rem %TEMPO_TEMP%
rem %TEMPO%
c:\Progra~1\Oracle\VirtualBox\VBoxManage setextradata %NOME% "VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled" 1
c:\Progra~1\Oracle\VirtualBox\VBoxManage modifyvm %NOME% --biossystemtimeoffset %TEMPO%
c:\Progra~1\Oracle\VirtualBox\VBoxManage startvm %NOME%
You'll also need the current time in epoh format, for this use the following script (save as "toEpoch.vbs", this visual basic script is called from the ".bat" script above):
WScript.Echo DateDiff("s", "01/01/1970 00:00:00", Now())
To run the virtual machine, simply execute the ".bat" script file above. No need to open the "Oracle VM VirtualBox Administration" interface.
I hope this helps.
Regards