It does take awhile for that area to adjust.

Just my experience; and I really hope this isn't your case, but back when I was a more casual rider, my sit bone areas would hurt after every ride, even the short 15-20 milers.. for days afterwards.

It wasn't until I started riding at least three times a week that the area grew accustomed to that kind of pressure. Now I just experience normal discomfort during really long rides, but I'm never sore the next day or 2.. or 3 like I used to be.