Your doctor is absolutely your best resource. See them before you start your walking journey.
Tell them exactly what your doing and how you plan to do it. I know that they'll love the idea of you starting a program of walking. And that the best idea is to start slowly but most importantly get started right after your appointment. That very same day.
Listen to everything your doctor has to say because they have seen it all. And they have years of incredible experience working with individuals designing fitness and nutritional programs that really work.
I know that my doctor is awesome...