I dont really understand your question. It may be true that women are more fertile after delivery but... no one can answer you whether that would increase your chance of getting triplets. Unless your family has triplets or twin then yes, there is a chance you might have twin or triplets.
If you are afraid there will be complication, do you want to wait longer? For me, my gynae said to wait for one cycle to complete and we can go ahead to try again.
You can refer some useful info here Trying Again