I just passed immigration now, and there was no lineup at all on this Sunday afternoon, took me 15 minutes to check-in and to pass immigration and customs....

But I also have made the experience that it can greatly vary between 15 and 60-90 minutes.

My advice would be have all your immigration/customs form pre-filled out... this is very important, it will save you time and hassle.... have also your connecting boarding pass etc....

then I would echo the sentiment that 45 -60 minutes are fine....