Is it better to email, call, or go to office in-person

[undergrad_2015]

I had contacted a former professor about research opportunity and he said we can chat in early May. When it is closer to May, do I email, call his office, or find when is his new office hours? I kinda feel that just dropping by would be too informal?

 

Also, what to expect at the meeting? Prof's email (shortened) says "we can meet in early May and have a chat".

Edited April 18, 2015 by undergrad_2015

[MathCat]

In 10 days or so, I would send a brief email to set up a time to chat.