I tried MB with little success, I've now moved onto OPKs, which seem to have worked for this first month.

Just a quick question though, the packet tells me that once I get a positive result (which means I've had an LH surge), should have intercourse within 24-48 hours. Does that mean that I ovulate the next day? The day after? I'm unsure what to take as my O day. So this month, I got a positive result on day 18, does that mean I O'd on day 19, or 20?? Just so I know when to take a HPT.