Acknowledgement after index creation

Hello, im trying to use OpenSearch ingestion by creating index after upload data to s3.
After uploading some folder to S3 in order to index its data, i want to get some acknowledgement when the index done to be created. It would also be a good solution that after each document that indexed by the data prepper ill get some trigger in order to apply some script to check how many document i have in the index and how many i have in my S3 folder.