$prefixSize = 4;
$datePrefix=date("Ym");
for ($i = $this->incrementsOffset; $i < $this->incrementsMaxLimit; $i++) {
                $nextIncrementProposal = sprintf('%0' . $prefixSize . 'd', $i);
                $nextLoginProposal=$datePrefix.$nextIncrementProposal;
                if (!isset($this->busyLogins[$nextLoginProposal])) {
                    $this->loginProposal = $nextLoginProposal;
                    break;
                }
            }