The latest issue of Sky & Telescope has diagrams of the situation for ISON
in December, and the predictions are all about seeing things just before
dawn, but their last image is for Dec. 5. The earthsky.org site shows an
evening scene for Dec. 18, which might well be correct -- it would be after
the comet has gone around the Sun, if it makes it around the Sun. What is
absolutely certain is that you can't possibly see the comet both just
before sunrise and just after sunset, on the same day.