Honey, for the most part, is 100% fermentable and will not leave a great of honey flavor behind. That said you can still add it and I would do it at flameout. I just made a honey kolsch and used some honey malt in my mash to get the honey flavor. Typically you get the best bang out of this malt by mashing, but you can steep it as well, it just won't convert without other base grains.