This depends on 1) how often you re-index to Algolia 2) The number of items you are indexing.
Very generally speaking, if you use the SKU re-indexing form those items are quickly indexed. However if you have a large number of changes sent to Algolia, those changes take time to build. This time doesn't have a guaranteed ETA.
Otherwise, you'll want to make sure that the indexing queue, if you are using this, is configured to update at the correct rate for your use case.
