Use a page like this :
http://wwp.greenwichmeantime.com/
Select your location from the drop down and it tells you your time (check its right) and by how much you are plus or minus to GMT.
in the UK we are GMT+1 which means 20:00 GMT = 9pm local time.
in much of Europe, they are GMT +2 which means 20:00 GMT = 10pm local time.
In the winter, the UK changes its time to be GMT, while Europe changes to GMT+1 (this is due to daylight savings changes). In other parts of the world they all do their clock changes or not at different times.
GMT itself never changes (it has no daylight savings), this is why it should be simplest if GMT is the base mark for the knockout start times.
So long as our mods know what GMT is, then all you would have to do is familiarise yourself as to your local time relative to GMT and you wont miss a start.