Unless your DH has a low count, you can BD each day. My RE was adament about BDing as much as possible the second that the OPK turned positive. She said that sperm production takes 72 days in total and every day a man has a full new batch. If you have sex multiple times in one day, each ejaculate will have less sperm. THe next day he will have as much as he did the day before.
So if your DH is normal, you can BD each day and that will give you a better chance of conception. The more sperm there, the better.