This is a question that many women ask after suffering a miscarriage through a blighted ovum. There are a few different answers and it may depend on both physical and emotional circumstances.
Physically many doctors say that you should wait for 2 cycles before TTC again. There are a few reasons for this and it can also differ depending on whether you had a natural miscarriage or any medical intervention was needed.
If for example you had a D&C then you may need to wait for a while for the uterine lining to get back to full strength. If the lining is not thick enough for a pregnancy and you try again the next month then you may well miscarry again.
If you had to use pills to start the miscarriage then you also may be advised to wait a few months as they can linger in your system and cause harm to a new embryo if that is formed soon after.
Even if you had a natural miscarriage then you may want to wait a few months because it can take a while for your cycles to get back to normal and it is also possible to have anovulatory cycles after a miscarriage (where you do not ovulate), so it may be easier to wait until your cycle is regular again.
Also, you are likely to be grieving from the miscarriage and you need to give yourself time to get over this emotionally as well as physically.
So, the best thing is to speak to your doctor. Some doctors may give you the go ahead to TTC straight away (especially if you are getting older and you feel like every month non-ttc is wasted) and if you are OK with this then go right ahead.