‘And the men who held Jesus mocked him, and beat him.'
In those days the beating of prisoners before trial was seen as a softening up process. It was seen as making them less able to defend themselves, and as therefore more likely to tell the truth. The mockery was also typical of the vast majority of mankind. But significantly, and unknown to its perpetrators, it was fulfilling Scripture. For remarkably Scripture had declared that this kind of treatment was exactly what would be meted out to the Coming One (e.g. Isaiah 50:6; Isaiah 53:3). (Nor did Luke probably have that in mind, for although it was perfectly reflecting that prophecy, had Luke realised the fact he would probably have made it verbally more like it).
The imperfect tense of ‘mocked' indicates a continuing process. This treatment would continue whenever Jesus was left in the custody of the soldiers between the different arraignments. After all the guards had to keep themselves amused and relieve the boredom of their watch, and they were inured to brutality. It is not therefore a question of when exactly this kind of treatment took place. It would take place constantly.