I am on the same boat as you since Im doing AI. Im sorry I cant give you a specific answer but ive been told that ewcm can come way before ovulation. Im also told that opks are not for everyone so Im not really sure which one you can count on. do you chart? do you temp? this might help, I started this month and Im told it can help pinpoint ovulation. I have been going on opks for 4 months and still didnt get pg... last month I went based on ewcm and I should find out if it took by the end of next week. pls post how things go.
thought I would also add that frozen vials are usually guaranteed I think it was 5 days, but they usually last longer.(of course he have to keep it in the canister) after you thaw it though you must use right away.