How to know before itself the time of ovulation so that we can have a better contact before in time to get pregnent.?

Couple of ways: Monitor vaginal mucous. The mucous will thicken and become stringy before ovulation. Also tacking your basal body temperature. Your temp will go up a few tenth of a degree with ovulation.

OPK better than BBT: If regular periods use an ovulation predictor kit (opk) between 10 am and noon starting on day 10 of your cycle. First morning urine is not as good. Try the ovuquick brand (look online for 9 pack) if a drugstore test doesn't work for you. The day of a positive test and the next 2 days are the most fertile. Opk goes + before ovulation, temp. Rises after. With irregular cycles see a rei specialist.