I find I get better every day. I normally have a stiff neck cause maybe I haven't been on the bike seriously for a year. By day 2 or 3, I usually start to feel good. Hardest thing for me is my schedule. I'm early to rise early to bed on the road and the reverse at home.
The ass and chaffing would be a huge problem If I weren't prepared for it. no undies, double thickness pile in the seat area, peneten, clean as required use polysporing if chaffed, ride B-17.
Feet can be a problem without cycling shoes. hands without tough gloves.