Database migration: SQL server to Postgres

We are seeking someone who has strong experience of migrating SQL Server databases to Postgres. We are in the process of migrating our application, and with that will come a change in database.
Objective is to have the database fully migrated so that we can run our app up against it, to verify it.
I need you to maintain full documentation for this. As well as the migration, I need a full handover document detailing what you did and how please, as this work will need to be repeated again in the future several times, and I want our team to be able to do it. If this goes well, we will probably use you for other things in the future, so please do your best work on this.