The Full Disk Encryption process resumes encryption 5 minutes after the system starts. You can restart, hibernate, shutdown, sleep the machine as normal and use it while encryption is in progress.
When encryption resumes after a system restart the Resume button will be enabled allowing you to resume encryption without waiting for the 5 minute countdown.
If you need to pause the encryption process there are two methods that can be used:
If the machine is a laptop, disconnecting the charging supply and running off battery will prevent the system from resuming encryption and will also pause an active encryption process.
If for some reason you need to stop the resume from happening more permanently then open the \Program Files\DESlock+ folder, rename the dlpepic32.exe or dlpepic64.exe application to _dlpepic32.exe or _dlpepic64.exe as appropriate, then restart Windows. This will prevent encryption from resuming until the program is put back to its original state.