I know no better way to set a "fixed" train/test period than what i stated before. Obviously LookBack and test period make a impact on WFO results, that's the same with almost any strategy you can find out there.

There'll be always some factors that will escape our control, that's why i think it's not so important to set a magical number of cycles or parameters and so on. Live trading will always surprise us.

The only rule i know about WFO is that your strategy should at least perform 50% of the ideal performance of a non-wfo test.

Again, this is only my opinion. I'd really like to read the advise of more experienced people.