Lol, do you wear cycling shorts? If so do you use chamois creme, I would advise both.
I recall my first foray back into cycling on a road bike a year ago, my arse was in agony for a couple of days after each ride. It does bet better, but it massively improved when I changed my saddle, got my sit bones measured at a local hargroves shop, and ended up with a new saddle which was recommended for my sit bone size, now I tend not to suffer any discomfort until after about 4 hrs in the saddle, but a few hrs after the pain has gone.
HTH, I'm sure others will be along soon with their experiences.