Sirenz, for my last c/sec I organized a midwife to come in with me and be our advocate. I was a private patient in a public hospital. If you have someone like that who is there on the day and can help support you, then you have a good chance of waiting to clamp. But otherwise, as Kelly said, it's up to the OB and anaesthetist.
I had to plan a c/sec at very short notice...it actually turned into an emergency c/sec just a few hours later...but having that midwife at my side was a great help to me and especially to DH.
If you have a planned c/sec, you will have an advantage because you can discuss this in advance with the OB and your desires should be in your notes. Just be aware that if for some reason your doctor is not there on the day, the replacement may well follow his own wishes. Also, you will probably have an anaesthesia consult before your EDC. Again this is something to bring up at that visit and have in the anaesthetist's notes.
If you plan a vaginal delivery, you can STILL ask for that to be in your notes, "if I have a c/sec here are my wishes". Unless the c/sec is a complete time crunch, you will have a few moments to talk to the anaesthetist and you can request delayed cord clamping at the time. It should be in your notes anyway, because under stress you or DH may forget to mention it. HTH!