I am in some kind of conundrum. Currently I am a grad student in Germany. Things are reasonably fine, but because of some bad luck I am not 100% confident that I will finish my thesis at the end of this year (as planned). I might need some more months (maximum 3, I hope), which in the worst case I could finish my work even without a salary. Still, I want to try and get done as close to the end of this year as possible.
Some sources (the Internet generally) tell me I should soon start searching for a postdoc position, especially because I am for personal reasons bound to a fairly specific location in the UK (not where I currently live, but where my significant other lives).
So what do I do? Start looking and applying for postdocs now, wait three more months (to give me the same leeway but with the added three months) or wait until I am actually done. Waiting until I am done is probably the morally right thing to do, but if it is taking me until March 2018 to finish, sustaining myself for potentially some additional months of job search will be financially problematic.
If I start searching now (or soon), what can/should I tell potential advisors? How common (if possible at all) is it to set the start day "somewhere between January and April next year"? I have a feeling this would hurt my application significantly, in favor of applicants that have a more well-defined timeline. What is the most common thing to do? I have seen others postpone their graduation, but most of them were planning to leave academia after that anyway, so had to prepare for a fairly different hiring process.
I am just worried that even if I find a position quickly after finishing, the start day might be months away and that would still leave me without any salary for a lengthy period of time. Any tips and experiences would be appreciated.