When is the best time of the day to have sex when trying to conceive and how many time should we have sex? In the day

Not really known. This has not been studied well in a scientific way. In my opinion it does not matter because sperm live for hours to days in the vagina and the uterus. Some advice focuses on the fact that the uterus contracts during arousal and especially during orgasm. Uterine contractions may help sperm get into the uterus.
Every other day. The best interval for achieving conception is every other day around the time of ovulation.
Timing of Sex. The time of day does not matter for getting pregnant. The frequency of sex can matter. We usually recommend sex every other day during the fertile part of cycle. The sperm live in the cervix and uterus about 2 days (reliably). The egg can only be fertilized for about 18 hours after ovulation (ivf experience). If sperm count low then too much or too little a problem. Good luck.
2, 1 and 0 days bef. Couple should begin to try to conceive 2, 1 and 0 days before ovulation.