I don't know that I ever felt "ready" or "not ready." To paraphrase Yoda, do or not do, there is no "ready" or "not ready." You either take the next step in your life, or you remain stuck.
Much of my life I have been guided by a feeling as to what was the right choice, or a sense that the way became clear, sort of like when you're hiking and it gets dark and you have to let your feet tell you where the trail is. When I divorced, it was because it had become clear to me that if I stayed in the marriage, I would soon be dead, and while the idea of being dead didn't feel all that awful at the time, I knew I couldn't abandon my kids that way. Many years later, I read a blog article which led me to consider that I might be trans, and that started me on the road that led to my transitioning. Each stage was just one more step on the road that felt laid out for me. (I'm very grateful for my trans foremothers who blazed the trail!)
As for SRS, it wasn't a matter of knowing that I was "ready," it was that that felt like the next step. I never felt any inner conflict or questions about SRS, and the only reason it took 6 years before I could get it was the arbitrary standards of the individual surgeons. The closest thing I had to any qualm about my "decision" was when it was time for me to walk to the OR, and I was terrified. But I've had a lifetime of being terrified and moving ahead anyway, so it didn't stop me.