In this period I have been applying for some postdoc positions. One of the main difficulties is that there is no central organization, so the times and practices for applying vary considerably even in the same country. Even being able to start a postdoc exactly when the previous one ends is not always simple.
Here I have a question about etiquette. What is people expected to do when moving from one postdoc to another one? A typical example would be a position which starts a few months before the previous one is finished. Or it is conceivable that one may have to accept a position in a short time, only to find later that he has won another position (for which he had already applied) which is "better" for various reasons, for instance it lasts longer or is in a place which is more favourable for personal reasons. An extreme case would be that on getting a permanent position while still doing a postdoc.
What is the expected etiquette in such cases? I'm interested mainly in what happens in Europe, if the opinion changes worldwide, but it is probably useful to hear from anyone about this matter.