You can review indexing when you have 1000 records indexed. It will be automatic but may take a few days to show up. You will begin to see a review button with the index button when you select a batch to do.
"You qualify to review records after you index 1,000 records in the indexing system. Then, you begin to see the Review button when you search for a batch to index or review.
As you index, learn to do the following:
After you have indexed 1,000 records, you will automatically be given access to review batches. The permission process takes a day or two.
To locate your indexing total, go to the Indexing page: