I just place a shortcut to my start.bat in my Windows Startup folder.
Alternatively use Windows Task Scheduler to start you "start.bat" file on log-in.
That's the odd thing, running it from startup folder doesn't work because it tries to run the script in windows directory. Changing the path in the bat doesn't fix this. Haven't tried running it as a task, hopefully that will fix it (though the AHK method works). Edit: just tried as scheduled task, same problem. Throws an error when it runs.