Hopefully this will be added to the documentation soon, but this is a very important piece that is left out and is learned the hard way.
Everytime you make changes by compiling the python code you need to run upgrade.bat before rerunning the server. This will cause the player database to be in sync with the baseline database (multiplayer.baseline) and will perform some sync options in the process. If this is not done you will get Genesis time mismatch errors. In order to prevent this follow these 3 steps.
So in short follow these 3 steps.
1. If you compiled the python code you need to run upgrade.bat
2. To run upgrade.bat find it in the default tmmokit install directory and run it with the argument of your game directory (default is testgame...so upgrade.bat testgame).
3. Make sure there are no errors and run your server again.
Once this is done the mismatch error should go away and you can connect to the character server.