replace now.After with !now.Before, insteading of checking for equality

mixing/mixclient/client.go

@@ -516,7 +516,7 @@ func (c *Client) prDelay(ctx context.Context, p *peer) error {
 	sendBefore := epoch.Add(-timeoutDuration - maxJitter)
 	sendAfter := epoch.Add(timeoutDuration)
 	var wait time.Duration
-	if now.Equal(sendBefore) || now.After(sendBefore) {
+	if !now.Before(sendBefore) {
 		wait = sendAfter.Sub(now)
 		sendBefore = sendBefore.Add(c.epoch)
 	}