Jury Summons question Baltimore City

So my sister got their first jury duty summons for May. She is available on the 26th (summons date) and filled out the qualification online but she knows she will be on vacation starting the 27th. Would she schedule a postponement now in advance or if she is summoned for the 26th, and it is not a one day trial but rather something needing her attendance for a week or two, would she then tell the judge that she cannot make it for those dates as she will be gone from the 27th to 30th (her friend is getting married, she already has transportation tickets and hotel reservations out of state).

Sorry I am not familiar with Baltimore city and she doesn't have a reddit.