How to get Imperator trait?

[Maeran]

I tend to get the imperator trait first, by sending my young generals against an obliging rebel army that has superior numbers but can't beat a FM with his body guards- 2 units of levy hoplites is a good one. Then I let him get back to his studies until a suitable war comes up and he is old enough, according to my house rules. Then my imperator gets first dibs on taking enemy cities and killing good size armies.