The M3 Pro is a small bump (if at all) over the M2 Pro tho, so it may not be worth waiting for unless the next Mac Mini comes with other upgrades like Wifi 7, more ports, etc.
Don't remember if it was in these forums, or on the TechBoards.net Apple forums, or an article somewhere on the web; but I read something about how the M3 Pro was great for coding/programming, because the efficiency cores actually did a ton of the work while coding/programming; so while the M2 Pro / M3 Pro performance difference seemed small on paper or with synthetic benchmarks (usually aimed at a different sort of number crunching), the M3 Pro was outstanding for coding/programming...
But then, if the pricing is anything like the M2 Pro Mac mini versus the M2 Max Mac Studio, once on goes beyond the stock M2 Mac mini configuration (non-binned SoC & RAM upgrade), then the base M2 Max Mac Studio made more sense (more CPU & GPU cores, double the UMA bandwidth, 10Gb Ethernet)...