I am 59 and had my surgery this past May with Dr. Mcginn, for me sitting on chairs without allot of padding was uncomfortable for any length of time even with the doughnut which will be your companion for around 8 - 10 weeks, this is one of those YMMV kind of things, everyone has a different tolerance to pain and heal at different rates, i felt good enough to go shopping almost every day three weeks after surgery, i went to a local trans meeting 5 weeks after surgery, though sitting on a sofa even with the doughnut for a couple hours was uncomfortable, i participated in a charity golf tournament 10 weeks after surgery, played 18 holes, everyone rode in carts, i pretty much stopped using the doughnut after this, 3-1/2 months i was back to bowling in my 2 winter leagues and just over 4-1/2 months i was back riding my road bike.
Taking a class twice a week is going to depend on how you feel, especially in the beginning, is the seating well padded, how long is the class, will you be seated the whole time, if needed can you get up and take a break from sitting.
Dilation schedules are not set in stone but especially in the beginning you will want to try to do the number of dilation's your surgeon recommends so you do not lose depth, if you are an hour or so early or late you should be alright, but i can tell you this, dilation will rule your life especially in the beginning, i watched old TV shows on my computer and listened to radio to help pass the time while dilating, you can read books, anything to occupy yourself.
Paula