? About Wondfo Ovulation Tests.....

Nira • Wifey.Mommy.Happy
If I keep a wondfo OPK (to compare it to the tests I take over the next few days) will it stay basically the same shade, or does it fade or anything? 
​I took one today and I feel like I'm close to ovulating, but not quite yet.  I think I'll get the closest guess to ovulation if I can compare lol