As mentioned by another poster(and a good point), there is in fact, a lot of 'prior art' out there.

Also, as mentioned by yet another poster, there are in fact existing schedulers which would handle this.

What you propose is certainly doable with Perl(and others). Again, I have to wonder how long the user will be waiting.
If the user is expected to wait a few seconds, no problem. If longer...? Regardless, I personally would have Perl put out
that "please wait for..." page. Your back-end knows what is going on, let it inform the front end. There is no penalty that I can
think of for doing it that way. To keep the user more or less engaged, have Perl spit out some javascript which probes the server
for the state of the job and updates the user every 10 seconds or so...

Just a thought... .