birthing ball and natural labor question?

A little background, this is my third pregnancy so most isn't new. However my first born has spina bifida so was a medically necessary C-section. My second born came just 20 months later and was a repeat C-section at 9 lbs though they had believed he was going to be much larger.

I'm now 20 weeks with our third. I never used a birthing ball with my first two or anything because I wasn't encouraged to do any preparing for labor with the complications I mentioned. This time, granted the baby isn't so big they consider a C-section medically necessary, I'd like to try for a vbac. I'm just wondering is it to early to start trying to prepare myself for labor, what can I do to help? I've never had anything more than braxton hicks and I know Dr has already said I absolutely cannot pass 39-40 weeks so I'm trying to mentally prepare as much as I can and physically prepare to hopefully labor on my own when the time comes.