I would wait until there is no detectable heartbeat before having a D&C. I've read stories about women who have been told to have it, but they refused because they wanted to miscarry naturally, but then when they did ultrasounds a week or so later, the baby was fine. It's completely up to you what you want to do, but personally, I would wait until no heartbeat is found.
I had a miscarriage in December and at first was in denial... I went to a different hospital and my blood was drawn for a quantitative hcg level and was repeated 8 hrs later (I stayed in the hospital) and my levels went from 31000 to 20000 approx. and was told by both hospitals that the only reason for levels to decrease like that that fast was because there was Jo longer a viable pregnancy. I then insisted an u/s be done and there was no hb (was 130 a week prior) and after a few hrs of crying and talkin with my husband we decided to have the d&c done... Now we're 10w2d with twins! If you have unfortunately lost the baby and he/she is now being held and told about you and how wonderful and amazing you are by god then I would have the d&c. Havin to go through labor with knowing the outcome is not what you want may be more traumatic on you, mentally. Good luck and I will keep you in my prayers. Hope this helps a little and I'm so very sorry for your loss. :,(