$a="test string x  x\nFeb  1 09:12:33  (";
if ($a =~ /^\w{3}\s\s\d/m)  { # /^Feb  1/
  $a =~ s/^\w{3}(\s\s)\d/ /;
  print "<$a>\n";
}else{
  print "no match\n";
}
#<x  x
Feb  1 09:12:33  (>