As someone who accidently had their baby in the car on the way to the hospital for my second birth, I can attest that although the entire labor may be the same length as your first, stages of your labor may go faster and/or may feel differently than your first. My entire second labor was the same 24+ hours as my first. However, the active labor and the transition were SIGNIFICANTLY shorter the second time. I also experienced significantly less discomfort the second time. So I kept waiting for it to be horrendously painful and thinking that the ways that I felt meant I still had hours like they did the first time, and it just wasn't as painful....until he started to come out in my bedroom. For example, the first time, I threw up right before transition, but then transition was a couple of hours. This time, I threw up right before transition, and transition was all of ten minutes.
I guess I don't have any advice except to treat this labor as entirely separate from the first and assess when you might need to go based only on how you are feeling and not how you remember your first going. That said though, having the baby in the car wasn't so bad
I should have just had another homebirth though!