Some time ago.
After killing all the Black Guards who didn't swear loyalty to Mira, Lucien led the group to the northeastern border of the Naga Kingdom as planned.
Mira was concerned that many soldiers still loyal to Tyrion had just bowed their heads to keep alive, but Lucien's draconic aura prevents people with that low soul power level from lying to him out of fear and respect.
That is, of the five thousand soldiers in that group, the four thousand who remain with them are genuinely willing to fight and die for Mira and the future of their people.
And they also already recognize Lucien as not only Mira's protector but also her husband, so they follow his orders just like hers.
Although the distance to the northeastern border is about many thousand miles, the group manages to get there in just six days, surprising not only Lucien but Lust as well.