<?php
//primeiro sábado de fevereiro de 2018
echo date('d-m-Y', strtotime('first saturday of february 2018')); echo "\n";
//segundo sábado de fevereiro de 2018
echo date('d-m-Y', strtotime('second saturday of february 2018')); echo "\n";
//terceiro
echo date('d-m-Y', strtotime('third saturday of february 2018')); echo "\n";
//quarto
echo date('d-m-Y', strtotime('fourth saturday of february 2018')); echo "\n";
//quinto sábado - se não houver passa para o próximo mes
echo date('d-m-Y', strtotime('fifth saturday of february 2018'));
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