knittedmittens I'm currently in the first cycle after my mc, lovingly known as the wtf cycle as that's what we spend our time thinking the whole way through! I've used OPKs this cycle as we wanted to start straight away but I'm not sure that I'd advise using them. I've ended up a lot more stressed out that I would have, resulting in a meltdown yesterday caused by a bfn (the straw which broke the camels back tbh).
I thought they were a good idea because my cycles have usually been regular, so I started them the day after the bleeding stopped. I was using the clearblue dual hormone test which you must use FMU for. I got a flashing smiley on the second day and then this continued for a week - the flashing smiley is supposed to be for about 2 days, so this was the start of the confusion. During that week I also bought one of the normal clearblue OPKs with the smiley face which appears when it detects the LH surge. I did these on the afternoon. I had 2 days of flashing smileys and positive OPKs in the afternoon, and then my am test showed a solid smiley and my pm was negative for 3 days - they were completely comtradicting each other.
After that week I thought it was over, so I stopped spending a fortune on sticks - very, very expensive if you don't ov within the usual timescale. It does tell you what day to start testing according to the length of your cycle so I suppose you could do that. However, you can't trust that your body will ov on it's usual time because in wtf anything goes! I started to get ewcm and stronger of cramps about a week after I stopped testing - which made no sense at all. So while I assume I'm in my 2ww I could,have actually only ov'd last week.
I said at the time that I wouldn't advise anyone to use OPKs during wtf, but it totally depends on how much you get stressed out. I'm still waiting AF or BFP but I've tested already and got bfn. I don't know if it's early or negative. The other thing to bear in mind is that OPKs detect the surge, but not ovulation, you can have more than one surge but usually only ov once, so you can't know which time it actually was. I'd temp tbh, it think it's more reliable.
Good luck, I don't mean to sound so negative but I started out very relaxed and now I'm in bits. I know others have had similar, the only positive was that I had something to focus on rather than being sad.