Vbac and big baby?

I'm 37 weeks and a few days.. Just had my appt today and planning on a vbac. Doc said I am measuring a week ahead and that he's gonna be big. Shouldn't I be worried the bigger the baby the smaller the chance of vbac? He didn't seem too concerned. Anyone have a big baby and successful vbac? Should I start trying to get things moving? I would love to deliver vaginally.