This is only a working hypothesis. The question demands further research for representations of Greek gods in medieval art before 1424/1425, specifically the 12 Olympic gods as they were developed in old Greek and Romans. Greek gods as planetary rulers of course were present prior to 1424/1425, but figures like Demeter-Ceres and Hestia-Vesta are not planetary gods, so their presentations should have been seldom. Filippo Maria Visconti used them - we should know, how "modern" he acted with this. So we've here a place to collect such data - prior to 1424/1425.
It's still empty - perhaps only, cause we didn't find the right book till now.
Also we're in research for any activities, which look like a triumphal procession - also prior 1424/1425. Filippo Maria Visconti had a triumphal procession in 1425 - that's known. What was similar and before that time?