Hello,
you can have a script reading the log for you.
$ awk 'BEGIN {latest="not yet this month"} /dist-upgrade/ { latest=last" "$0;} { last=$0; } END { print latest }' /var/log/apt/history.log
Start-Date: 2015-10-05 23:46:46 Commandline: apt dist-upgrade
$ perl -wlne 'BEGIN {$latest="not yet this month"} /dist-upgrade/ and $latest="$last $_"; $last=$_; END { print $latest }' /var/log/apt/history.log
Start-Date: 2015-10-05 23:46:46 Commandline: apt dist-upgrade
That perl example seems to imitate the awk style. I'm sure there are other solutions, that are more "perlish".
greetings
musca