Consultant Leonie replies: It's recommended that at least a year is left between births after a Caesarean, owing to fears about the scar splitting during labour if the interval between births is very short. There isn't much evidence but there doesn't seem to be any risk if the gap is a year or more, and only a small risk if the gap is less than a year. But as it's already six months since your Caesarean, there's no reason why you shouldn't try again.
It's a good idea to try sooner rather than later as fertility does decrease with age. Also, a Caesarean can reduce the chances of conceiving quickly for some women. The interval between the births shouldn't affect your decision about whether to have a vaginal birth or an elective Caesarean next time around.