Reminder: 32-bit apps will not work in Catalina.
If you use your computer as your main work machine, hold off on the update. You're bound to run into a random forgotten app you use every once in a while that's no longer supported.
To see what's still 32-bit on your mac, go to:
Apple icon > About this mac > system report > applications > then click the 64-bit column to sort. No will be 32-bit apps.
To see what's still 32-bit on your mac, go to:
Apple icon > About this mac > system report > applications > then click the 64-bit column to sort. No will be 32-bit apps.