Help! Should I take plan b???

Okay so I had sex at like 1 this morning. According to <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">Eve</a>, I have already ovulated and am 7 days from my next period (so like 3% chance of pregnancy). My question is, does plan b still work if you have already ovulated? Should I take one or not?