Azir, Conquering Sand help.

only played a few games with really enjoyed him.

One thing that's been causing me some frustration is his Q, Conquering Sands, while the game does display the minion charge line markets before you click to execute. It seems as though has a bubble around him that determines maximum range that a minion can charge.

This has caused me more than once to send a minion out only to have them fall short or in some cases charge backwards towards me instead of the marked direction.

Are there any rules of thumb, or possibly other game feedback that I miss seeing before using the skill?

How have you coped with it?