whwn to start testing? only once per day is enough?

[lovsec]

i am trying to conceive since 3 months for 2nd baby(1st child is 4.5 years,removed copper t 3 months back) , this is 4th cycle ttc. today is 7 th day o my period. my period ranges from 26-29 days. i used calender and had BD every other day ,but didnt conceive.so thia cycle i bought OPK with 6 strips. when should i start testing it? from day 9?when to have sex?we can have s*x only on the night.so should i test only at 2.30 pm,is that sufficient ? i generally have cervical mucus only one day and only one time during pe*, what should i do? please help