Changed date to July 15 to provide buffer

Author: Luis Cabrera

articles/search/index-ranking-similarity.md

@@ -14,11 +14,11 @@ ms.date: 03/13/2020
 # Ranking algorithm in Azure Cognitive Search
 
 > [!IMPORTANT]
-> Starting May 1, 2020, newly created search services will use the BM25 ranking function, which has proven in most cases to provide search rankings that align better with user expectations than the current default ranking.  Beyond superior ranking, BM25 also enables configuration options for tuning results based on factors such as document size.  
+> Starting July 15, 2020, newly created search services will use the BM25 ranking function, which has proven in most cases to provide search rankings that align better with user expectations than the current default ranking.  Beyond superior ranking, BM25 also enables configuration options for tuning results based on factors such as document size.  
 >
 > With this change, you will most likely see slight changes in the ordering of your search results.   For those that want to test the impact of this change, we have made available in the 2019-05-06-Preview API an ability to enable BM25 scoring on new indexes.  
 
-This article describes how you can update a service created before May 1, 2020 to to use the new BM25 ranking algorithm.
+This article describes how you can update a service created before July 15, 2020 to to use the new BM25 ranking algorithm.
 
 Azure Cognitive Search will be using the official Lucene implementation of the Okapi BM25 algorithm, *BM25Similarity*, which will replace the previously used *ClassicSimilarity* implementation. Like the older ClassicSimilarity algorithm, BM25Similarity is a TF-IDF-like retrieval function which uses the term frequency (TF) and the inverse document frequency (IDF) as variables to calculate relevance scores for each document-query pair, which is then used for ranking. While conceptually similar to the older Classic Similarity algorithm, BM25 takes its root in probabilistic information retrieval to improve upon it. BM25 also offers advanced customization options, such as allowing the user to decide how the relevance score scales with the term frequency of matched terms.
 
@@ -53,9 +53,9 @@ PUT https://[search service name].search.windows.net/indexes/[index name]?api-ve
 }
 ```
 
-For services created before May 1, 2020: If the similarity is omitted or set to null, the index will use the old classic similarity algorithm.
+For services created before July 15, 2020: If the similarity is omitted or set to null, the index will use the old classic similarity algorithm.
 
-For services created after May 1, 2020: If the similarity is omitted or set to null, the index will use the new BM25 similarity algorithm.
+For services created after July 15, 2020: If the similarity is omitted or set to null, the index will use the new BM25 similarity algorithm.
 
 You can also explicitly set the similarity value to be one of the following two values:   *"#Microsoft.Azure.Search.ClassicSimilarity"* or *"#Microsoft.Azure.Search.BM25Similarity"*.