Just a little run down i have a 6 wk cycle.

This is my first time charting.

We want to conceive soon, preferable this month.
I read that i should start using OPKs about day 20ish. Is this right? or should I just start using OPKs when I see CM?
I have purchase 40 OPKs & 10 HPT thru Amazon and have plenty to spare. What do you experienced charters think I should do?
Sorry that I post so much... I am still new and am trying to learn