i never liked opks...i just used fertilityfriend.com to chart my temps and watch for ovulation...also i could never bring myself to check cm...but i did (and still do) used mineral oil to help the swimmers along.
if you are unsure about when you did/will ovulate, try to
every 2-3 days if his swimmers are up for it
you can ask any question here
best of luck to you!
