How long does it take for a recruiting process to finish? I think the title says it all, but here it goes. I am a final year PhD student in pure mathematics. My PhD has been running smoothly and I will graudate on time next summer. 

This year I started applying for postdoctoral/assistant professor positions in Europe and in United States. The reviewing processes for these positions have already started, for example the earliest one started in mid December. 

As times passes I start to worry that the reviewing process will take longer than I expected. I understand that the people in the search committees have other things to do an that they may have large numbers of applicants to review. But as someone who will be unemployed next September, I am worried that there might not be enough time for me to look for alternatives if these applications turn out to be unsuccessful. 

Hence, I would like to ask what the normal period of time is for a recruiting process to finish. A side question might be if I would be notified if my application was unsuccessful. In a few job announcements it is stated that only the successfull candidates will be contacted. Hence if it is not stated otherwise in the job announcement, can I assume that I will be contacted no matter the outcome?
First off, timings are very different in different countries. I have experience applying in Germany, UK, US and Sweden, with radically different time scales. The US runs on a very steady clock, where there tends to be a season for applications, for interviews, for notifications, and relatively few events happen outside this rhythm, while elsewhere is much more anarchic with respect to timing. 

Shortest time periods I have had in the UK where a polite refusal has shown up as quickly as within about 2 weeks after the deadline.

In the US, you would usually apply during September-January, interview January-March, and be offered a job February-May or so. Slightly different timings are in effect for postdoctoral positions versus professorships, and there tends to be a second round of applications when schools scramble to cover teaching needs for the fall.

My experience with the US also indicates that you should not expect full information from everyone. Finding out you were not considered by simply not hearing anything from the school for several years is not an unusual situation.

UK schools have been diligent about letting me know one way or another.

German schools have sometimes delayed up towards 2-3 years before letting me know.

And the Swedish system is a beast almost entirely unto its own. For one thing, the process is utterly transparent: the list of applicants, as well as external reviews of the candidates and the minutes of all the committee meetings are all a matter of public record, and is usually distributed to all candidates directly as a matter of courtesy. The process is one of the lengthiest I have ever seen — it is in no way seen as unreasonable that well over 1 year passes from application deadline to notification.