Depends on your student, and your school, and you.
We have taken our kids out of school several times, usually in October although this year it will be 4 days in April. Our kids are 8th grade and a junior. They are in a private Christian school, and it's tough academically. Here is how I handle it (and so far, we have been 100% successful).
1. We schedule our trips with the blessing of our principal. I sit down in her office and together we look at the school calendar far in advance. We pick a time right after a grading period ends, never at the end of one.
2. I make it a point to speak to or e-mail each of their teachers individually as to our plans. It makes extra work for them to get assignments ready early, but they are so appreciative of getting advance warning that they always cooperate fully.
3. About 1 to 2 weeks out I provide an assignment sheet to each teacher that they can fill out with their assignments and also any notes or comments at the bottom, then there is no misunderstanding about what is or isn't due.I follow up with each teacher until we have all of them collected.
4. Our school's policy is that tests and quizzes have to be taken before leaving, homework is due upon return. My own policy is that if we are going on vacation I want the kids to enjoy it as well and not have to bring homework with them, so I make sure and ask for the assignments early and my kids are usually able to turn everything in before they go. And usually their teachers offer to let them take quizzes and tests when they get back, even though the official policy is otherwise.
5. I follow up with each teacher, either in person or by e-mail, to make sure they have everything they are expecting and that the work has been done well.
6. We are apparently one of the more successful families in our school that does this. Our CEO stopped me one day and said he wished I could give a class to other parents about how to take kids out of school on vacation.
7. Having said all of this, if your student really has to work in their classes, or is less than an A/B student, the struggle to catch up will not be worth a few days of fun. And remember that the grades your student gets their junior year are the ones that you use for college admissions so you do not want to jeopardize that.