The rules say you select your Stance before you roll Initiative.

I found a cheat sheet online that suggests you roll Initiative first and then declare Posture in reverse order of Initiative.

I see the benefit of the second method, but is that official? The first method seems clumsy to me.

In 4th Edition, you pick Stance first then roll initiative. This makes it little trickier so people won't go Full Attack simply because they won initiative, or Full Defence because they lost it so badly. Remember that people also get an ability to influence their Initiatives with Void Point (+10 is often difference between "go last" and "go first"). Getting to declare your stances after seeing Initiative would lead to...swingy choices.

Another thing is that in 4th Ed, you get to switch your stance at start of YOUR turn. So stances need to be picked first, because otherwise people would be in combat with "no stance".

It's less complicated than what it seems. Try playing it, and you'll see that is easy.

Reading L5R 4th ed. core rules page 84 (and page 81) and understanding the difference between Round & Turns one can say that:

• During the first Round of a skirmish you assume Stance during "Stage 1": which means just before you roll Initiative.
• In the following round there is no "stage 1/Iniatiative rolls" and this means that you keep your stance until you change it.
• During following turns you can change Stance at the beginning of YOUR TURN (so called "Stage 2") NOT ROUND, which means that if there are other turns before you in the same round and you are attacked by others, you'll still be in the stance you were in the past round...since your TURN has not come yet and you did not have the opportunity to switch stance.