If your quota generation happens using time evaluation, stopping the time evaluation will take care of generation of absence quotas.
You need to make sure that you transfer the quota balance to the new time system.
Also, if you are running payroll in SAP, then you will need to bring your time wage types and overtime payments in IT2010. If your payroll is not being run in SAP, you will need to send time data to your payroll provider for payroll processing.
Also, you need to discuss with client about the reporting requirements.
I hope this helps.
Thanks and regards,
Vivek Barnwal