OPK expiration??

So, my hubby and I are trying again. I had my period last Saturday the 10th. I have very regular periods, which means I’ll be ovulating around Friday/Saturday. But yesterday and today I have been feeling crampy and have a lot of CM...so I happened to find an old First response opk (still in package, but no box). The last time I used OPKs was about 3 years ago while we were trying for our daughter.

It definitely appears to be positive, but it’s so early for ovulation and I just don’t know if I should trust this test. What do you all think? How long to OPKs last (I wish I had the box with expiration date)?