Keystore not working for me,help please

i’m did keystore step by step form tutorial but when i still can’t upload .apk to google play
they said “You uploaded an APK signed with a certificate that is not yet valid. You need to sign your APK with a certificate that is currently valid” help please

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This might help (someone seems to have something similar) : android - APK signed with a certificate that is not yet valid - Stack Overflow