When is applying for a postdoc too early or too late?
Actually, what you described seems very familiar and I'm sure it's the same for a large fraction of Ph.D. candidates. So relax a bit :-)

But - I have to say that, reading between the lines of your post, I'm uncertain that you should even be searching for a post-doc at all:


You express a desire to find employment that sounds at least as significant, if not more so, than your interest to continue your research.
You are not speaking in terms of what you want to do research-wise but where you need to be geographically.


1. First figure out / soul-search whether what you really want is to find a post-doctoral research position.

Are you absolutely sure that you want to pursue a career as an academic researcher, right now? Are you sure a stint in industry (or other non-academia employment) is not something you would find satisfying, interesting, relevant? 

(To Op, specifically:) Maybe you are and your motivation and orientation is perfectly sound, but I'm getting a 'vibe' that this might not be the case. 

If you're certain that a post-doc is indeed what's right for you to do next, then

2. When the conclusion of your Ph.D. duties is in sight, it is time to start searching for a post-doctoral position.

The research groups / departments with which you'll inquire about open positions are very well aware that prospective availability is sometimes up for change, particularly in your case. Do not hesitate to say "I expect to conclude my Ph.D. in between X and Y months". Now, it's possible that someone might tell you "I need an extra researcher who's willing to start yesterday to get ahead on some funded research project" - and won't accept you on that account. But, well, that's life - and they won't think less of you because you're not done yet; don't drive yourself mad in some impossible race.

3. Sometimes you don't find a suitable post-doc position even if you search diligently and on time. Think about contingencies.

Academia is never very well funded, positions are scarce, and in your particular case there are some tight constraints. I know this is not very encouraging advice, but it's better to recognize this possibility and learn to live with it than spending the last months of your Ph.D. in dread of it being realized. That's really not a good emotional state to be in - and it won't help your work, either.