Stan wants to know if he should wait until Big Sur or upgrade to macOS Catalina now? Leo says that you have to upgrade to Catalina first, since it eliminates all 32 bit apps. This will give you time to convert your other 32 bit apps to 64. It'll be pretty straight forward. But moving up to Big Sur may be more problematic because of how they approach kernel use. But you could wait and see what happens and stick with Mojave until Big Sur comes out and then see if you have to. Why do it twice if you don't really have to?
But regardless, backup before you do any system upgrades. Just in case.