You will get arguments strongly on both sides of this debate and will have to come to your own decision ultimately. My DS was done by plastibel at 2 days old and has had no side effects. A friend did not get her DS done and had to get it done at 2 yrs because of some medical problem (can't remember what will ask her) and said it was very upsetting and hard for him so she got her next DS done at birth and he was fine. I have taught children who have had to have it done later (9 or 10) for infection problems and they have had to miss sport for weeks and been quite embarrassed about it at school afterwards.
Good luck deciding!