Monitor checkpoint firewall security services expiration

I'm looking to figure out how to get days until from a SNMP string to monitor subscription expiration for security services on our Checkpoint firewalls

The SNMP OID outputs the expiration date as a string in this format: Fri May 21 00:00:00 2021

I'm thinking the best approach would be to create a complex datapoint and pull the snmp data via groovy script, then compare it against the current date, and have it calculate the difference in days.  Similar to monitoring SSL certificate expiration.  Does anyone have an example of this type of script?