So this is my second baby and I thought things would more or less be the same (they have not been) so I'm wondering about the earliest signs of labor?

With my first I was induced and I went from nothing to full on labor in less than an hour, no gradual build or time to work into it. Right now I am 37 weeks, set for a repeat c-section in 2, but something feels off. I feel 'crampy' down low in my pelvis on and off but not like in pain. My arms and my legs are randomly going weak. Is this what early labor feels like, when you don't skip it? Any advice is greatly appreciated, thank you all.