It is possible that your antivirus, firewall or security restriction on the computer is delaying the start of your recording after the 3,2,1 countdown.
To verify this, here are the steps to follow
1 - Simultaneously press WINDOWS and R on your keyboard to open the Run window:
2 - Type cmd in the field and then press Enter
3 - Copy and paste "C:\Program Files (x86)\Momindum\Momindum Maker\bin\ffmpeg.exe" in the window and then press Enter
If the text in the yellow frame takes more than 2 seconds to appear, there is a problem here.