You don't say what should happen if the comparison fails, but given
$ cat -n UAT1.txt
1 UAT - NODE1,May18;21:00;HIW.ear
2 May18;21:01;O.jar
3 May18;21:01;Com.jar
4 May18;20:59;D.jar
5 May18;21:01;F.jar
then using perl, with the Time::Piece module:
$ perl -MTime::Piece -F';' -pe '
if($. == 1) {
($s,$md) = split(/,/,$F[0]);
$t0 = Time::Piece->strptime($md . $F[1], "%B%d%H:%M");
next
}
$t = Time::Piece->strptime($F[0] . $F[1], "%B%d%H:%M");
die "Timestamp out of order" if $t < $t0;
' UAT1.txt
UAT - NODE1,May18;21:00;HIW.ear
May18;21:01;O.jar
May18;21:01;Com.jar
Timestamp out of order at -e line 8, <> line 4.
Note that it's not clear from your example whether the month specifier should be %B or %b since you happen to have chosen the one month whose English full name and abbreviated name are the same.
You could do something similar with GNU awk (gawk) but you'd need to roll your own strptime using string functions to wrangle the elements into a format suitable for mktime.