delayed cord clamping

I want to leave the cord attached to my son until it turns white (I've read it usually takes about 5 min) at first I wasn't going to leave it that long and I was going to donate to the cord blood but after research I've decided that I'd rather my son get all of the nutrients and stem cells instead, there are tons of benefits to this. But when I went to L&D to have a stress test done the nurse was asking me different things and one was about the cord donation and I said no I want it on until it turns white and she made some remarks about how it could be used for other babies and I just thought her response was a little rude since I'd rather help my child first. Anyways just wondering if anyone else has done it this way