YOU will not be standing in front of a jury, calling witnesses and presenting evidence and cross-examining witnesses for the defense and filing motions and all of the other things your lawyer does. So it is YOUR LAWYER who must answer this question.
It is typical of every trial, in front of a jury or in front of a judge. The court needs to know how much time to set aside for individual cases so they can plan their court docket. A trial that runs longer than expected pushes other things back, and a trial that was scheduled to last two weeks and was over in two days leaves a hole that might not be able to be filled by other cases. Both are bad, but that one is worse. Dead time is always the worst.
If for some reason you are trying this yourself instead of using a professional, aside from what they say about people who represent themselves having a fool for a client, you will have to estimate the amount of time you think it will take to present your case, have all of your witnesses there and ready to testify and be cross-examined, present your evidence. That's what the court wants. They will ask the defense for their estimate based on what you present them, and the court will make its own assumption of procedural time. You are on your own without a lawyer.