My post on the logistical aspects of giving notice has been among my most popular, and continues to recieve significant traffic. First, given how much time and energy graduate students invest in their programs, it makes sense not to burn bridges when you leave. Second, I like to think that this post provides an opportunity to plan for the future rather than worry about it: leaving involves so much soul searching that it can be really constructive to channel that energy into the actual steps that action involves.
While that post dealt with the process of infoming advisors, Libet asked an excellent question in the comments about when the best time to give notice is. Do you wait for the end of the semester?
I ultimately decided when to give notice based on the TA selection deadlines. Drawing on my time in the private sector and the ritual of the traditional two weeks notice, it made sense to me that I should let everyone know with enough warning that my replacement could be lined up. Our assignments were normally finalized and announced in mid December so I gave notice the first week of the month so that the TA coordinator had one or two weeks to make adjustments and do some on campus interviews since she would have to hire outside the department. She also had the built in cushion of winter break for her to make arrangements.
Concerns Over Giving Notice too Early
I think the biggest concerns with having the conversation too early in the semester are concerns over grades (though in graduate school these concerns tend to be less a problem) or if you are leaving at a degree milestone and have concerns your advisors will lose interest or not pass you. The reality is once you quit most departments will just want to pass you out. I also worried if I told my advisor too early she would find a way to talk me out of it--though you will get questions regarding whether you are just burnt out with end of semester stress if you wait.
There is also something about deciding you no longer have to do something you hate that makes finishing out your time increadibly difficult. When I quit a job many years ago I had expected giving notice would lead me to feel relieved. Instead it made the tedium of my responsibilities almost unbearable. Once I had given myself permission to leave, the fact that I was still there even if only for a few more weeks was more painful than I anticipated. If you have a major milestone like a thesis due, you just need to make sure that you will have the energy to get across the finish line.
Finally, my biggest concern on timing had to do with concerns over not having any employment. I ended up giving notice without a job lined up because by that point I had decided I would rather work at Starbucks than stick around an extra semester, and it all worked out fine. The benefit of being paid poverty level wages is that pretty much ANY job will pay more. That makes it a bit easier to quit in some ways.
So to all of you considering when and how to notify everyone about your decision good luck! This process is ultimately about finding the right balance of what works for you, so while it is important to consider the consequences of how you go about executing your decision don't overthink it. Think it through, then listen to yourself and do what feels right. Just remember, this too shall pass and taking the first step toward asserting what works for you and what doesn't is a powerful move with the potential to set things in motion.