How to migrate Traditional Pega SA application to Constellation Incremental approach?

We have the Pega traditional applicatio in-place. There is a need to migrate the sales automation traditional to Constellation application incrementally.

Considering the user should access the exisitng traditional casetypes with a increamental roll out of each casetypes (ORG,ACC,CON,Renewal,Endorsement)

What is the best approach to move ?