I think a lot depends on how far along you were. A later MC is a lot for the body to recover from so sometimes it might be wise to wait a bit, a chemical isn't that different than a normal period. Emotionally only you know when is the right time. I had a chemical last year then we TTC once right away the next cycle before we decided to wait a bit longer... too late I was pregnant! Emotionally I think it was a bit soon for me to be honest but I'm happy to be the mother of a 1 month old girl now!