How soon is too soon to give notice to my employer

Hi all - I wasn't able to find anything about this so excuse me if it's already been addressed.

I do have a bit of a unique situation so here goes:
My family is working on relocating to the UK.  Due to several different circumstances that I won't bore you with here, we sent our son ahead of us so he could start school in September and the rest of us will go out there next summer.

My employer and coworkers have no idea that we are planning this move. They know my son is in the UK but they think it's just for the rest of the summer.

I don't want to be having to watch what I say or lie outright so I'm thinking I should at least tell my boss that this plan is in motion.  Then at least I'm free to speak about what my son is doing and not being deceitful.

I realize that I don't have to tell them now, but I feel like in this situation it's a good idea.  I honestly don't think they will let me go or anything because they are a small company and I have a great working relationship with everyone.  Because of that I don't want to look like I am keeping something from them.  It doesn't feel right and makes me look a bit dodgy.

What say you?

I'm not there to gauge the rapport between you and your boss(es), or the turnover rate at the company, or how long it takes for them to hire somebody, or any of a myriad of details that would weigh in to my decision, so I can't really tell you what you should do.  But if you have a good relationship with the people there (if you would consider them friends), I tend to agree with your desire to be above board and let them know what's going on.  I don't know what your work is, but giving them a heads up gives them an opportunity to plan for your departure so they're not left in the lurch.  Plus, you can help train your replacement if that's necessary.

At my last job, I gave a month's notice.  But this was because my departure was extremely flexible, and I had a backlog of cases to finalize and I didn't want my colleagues to inherit a stack of partially-completed appeals with my terrible scribbled notes.

If you do decide to tell them, stress that it's a year-in-the-making, and until visas and boarding passes are in hand, it could change.  Tell them you are not giving notice now (and that when the time comes, you will give them proper notice)... you just wanted to let them know that it's a possibility.

You and I are definitely on the same wavelength!  I was thinking more of an informal conversation about our plans because after all, there is no guarantee that I will be able to go back next summer although my husband and daughter will definitely be going.
It would be impossible to keep this all secret - it's already been so difficult both practically and ethically.  Thanks for helping confirm what I already knew!

I verbally gave my coworkers and managers a heads-up several months in advance. This was partly because I was stressing out and couldn't keep my mouth shut about it, and partly because I was pressing them to hire someone external to replace me. I then gave my formal notice about 6 weeks ahead of time. Of course they didn't hire a replacement, just "promoted" someone internal who had zero experience at my role, but no skin off my back....

I gave my employer 3 months' notice, because I was working in a highly specialized position and knew it was going to be difficult for them to find someone to fill it. Of course, they didn't start searching for my replacement until about a week before I left, so "d'OH!!!!"      .  Turned out they couldn't find anyone for over two months, and my poor manager was at her wits end trying to do my job and her job.

Oy. So, there's no right answer as to how much advance notice to provide, I guess. 

This is a pretty old post by now, but I think it all depends on your relationship with your employer/boss.  I told my boss my plans almost a year ago.  I knew that my job was safe, and I want to do everything I can to go out on good terms and remain eligible for re-hire in the US if we ever go back someday.  Also, my employer's parent company is based in the UK and I may end up applying for a position there once I'm settled, provided my spouse visa is approved.