help with OPK

Hi, so this is my first time using OPKs and I've been using it since my fertile window started. 
(I'm using ClearBlue digital OPK
Yesterday I had an empty circle (which  means no ovulation) 
And this morning I woke up to a smiley face ( which means I'm ovulating) 
Now does this mean that I'm currently ovulating and I have 12-24hours to DTD?? 
What happens if we DTD last night and I woke up to a positive ovulation sign this morning. Does that help in anyway? 
I know I'm freaking out over nothing but I just don't wanna miss the opportunity I have :(