Are informal inquiries about postdoctoral positions liable to be perceived negatively? I will graduate in 6-8 months with a PhD in physics and am looking to contact potential postdoc advisers. I will be applying to positions without an advertisement or prior contact with the potential advisers. I have been told by my current PhD adviser that if I wait until I just a few months before graduation, he will make the initial contact for me. I am conflicted because I understand many postdoc positions are planned and filled up to a year in advance. 

I don't want to lose out on these positions, so I first want to make informal contact on my own. However, I don't want to jeopardize my chances of getting a position by sending out a poorly received informal email. I'm wondering specifically how informal emails are typically perceived in these situations. Are they liable to be perceived negatively by those professors expecting a more formal process?
Informal inquiries are not liable to be perceived negatively: An informal inquiry is a very good way to make first contact before sending over more formal items such as a CV, letters of recommendation and proposed research ideas. A thoughtful email with some very brief and basic information about yourself and your interest in the potential lab is more likely to be read and replied to (no information overload). After initial contact is made, the more formal process will then be more directed as information about timing and funding may be provided.