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?