Incremental Migration After Changes to Files & Extensions

Question

I am planning to migrate Magento V-1.9 to V-2.1 with following steps.

Migration is planned as follows.

Looking for an expert advice:

Step 1: Migrate all Existing Data (Orders, Customers, Settings) to 2.1

Step 2: Start Installing Missing Themes and Extension. Configure it accordingly.

Step 3: Do the Delta Migration of Orders/Customers/Products.

Is there anything which can go wrong during delta migration?

I have gone through this advice: Best plan about delta migration

My major concern is, new theme installation should not break the delta migration.

Answer 1

First thing first: http://devdocs.magento.com/guides/v2.0/migration/migration-plan.html

Incremental migration enables you to migrate only the changes made in Magento 1 since the last time you migrated data.

These changes are:

1. Data that customers added via storefront (created orders, reviews, changes in customer profiles, etc.)

2. All operations with orders in the Magento Admin panel

so if your last migration was successful than delta migration must work properly unless you changed anything in the Database structure.