Adding honey to the boil removes a lot of the aroma, and the yeast goes berserk on the simple sugars, creating fusel alcohols unless you keep the ferm temps low. Then more flavor is stripped out with the CO2 production during fermentation.
So I would wait until the primary is about 2/3 finished, definitely a couple days after the krausen has fallen and fermentation has quieted down quite a bit. You got to eyeball where the process is about. Not that critical, though. Then add the honey.
You may want to pasteurize the honey you bought for all security, although reading some of the mead makers threads here can give you some extra wisdom. Diluting the honey with a bit of sterilized (boiled) water also makes it easier to mix into your beer. You don't want it to lay on the bottom, so a gentle stir will be needed.
And that's where it will help to first rack it off into a glass carboy (small headspace), and ferment a true secondary at a low temperature.
Maybe someone else can chime in.
Depending on how thick it is, honey adds 35-42 points of fermentables per pound per gallon. So 2 pounds of honey (say at 36 points per pound) in 6 gallons raises your beer's gravity by around 12 points (72 pts/6 gal).
You can keep your alcohol level the same by eliminating equivalent points (72) when calculating and brewing your recipe. Reduce malt or extract.
Since your beer will be more fermentable because of the honey (simple sugar), mash higher and/or add some more crystal malt to balance out.