When can I try to conceive again?

I had a D&C today. I would have been 8 weeks 4 days but the baby didn't make it.
We have been ttc for over 3 years and finally got pregnant with the third round of <a href="https://glowing.com/glow-fertility-program">IUI</a>. 
I am really sad but I desperately want a baby. How long do I need to wait to try again? The doctor didn't say today but I know that many of you have had a similar experience and may be able to give me an immediate answer. 
Thanks for your help.