Hopefully this will answer you're questions about how I managed this. I have a digital SLR, so there is no shutter lag essentially. How I compose the image is get myself setup where the majority of the lightning is striking. (When it's this far away there is definitely a 'predictable' zone.

As for 'when' I use bulb mode. This picture was around 8:30 pm (so dark already), I had the aperture at 6.3 and used a 37second shutter. Usually I guess at how long to leave the shutter open. It really depends on the amount of lightning...lots of bright lightning usually gives me about 30 seconds, whereas little lightning I usually go closer to 2 minutes...although have done as long as 4 minutes!

I use a tripod and remote control to ensure there is absolutely no shake and usually I have to experiment with all the above to get the right timing.

I also always wait until the storm is past me and chase it a bit...usually try to find a nice location with a good long view.

Anyway..hope all this helps! Try it out
Thanks so much for the kind comments about the shot and the exposure and tonal range!!

Cheryl