When you get a summons for Jury Duty you'll get around 10 days notice for your appearance at court for Jury Duty.
What happens is a computer process randomly selects your name as a Juror and then when you get the Jury Summons you're supposed to show up to the courthouse as soon as you get the jury duty summons to make arrangements and find out the date you need to start showing up for Jury Duty.
However you can always try to get out of Jury Duty if you can prove hardship or prove you have mental health issues or cannot appear as a Juror.
Also you could just throw the Jury Duty Summons out which is what I've done several times and never have been in trouble for it.
They cannot prove you got the Jury Duty Summons letter unless you are served in person with it or by certified letter.