C-section question

I've just scheduled my repeat c-section. My doctor scheduled it for 39 weeks. This will be my 3rd child. 1st was natural and 2nd was a emergency c-section. I've never made it to the 39 week mark. Both my kids have been big babies, coming early. My question is since it's a planned c-section no matter if I go before the 39 weeks, do I still wait till my contractions are 3-5 minutes apart before I head to the hospital? Or do I head in when the contractions start and are steady?