‘And after five days the high priest Ananias came down with certain elders, and with an orator, one Tertullus, and they informed the governor against Paul.'
The importance attached to Paul comes out in that the High Priest came in person together with some leading elders and with a trained advocate in order to charge Paul. And there they laid the case against him. ‘After five days.' See Acts 24:11. This will be calculated from when the trouble first began. Note that Luke is able to give the name of the advocate.
After arriving in Jerusalem Paul had met with the church, immediately spent a few days of purifying, and had five days earlier been initially arrested by the Romans, making ‘twelve days' in all.