currently, the DBAs gets a heads-up about a new requested wiki via a "Prepare and check storage layer for XXX" task. Previously, the wiki creator created the wiki at s3, as suggested at https://wikitech.wikimedia.org/wiki/Add_a_wiki. However, that practice is about to change, as s3 is filled with a lot wikis already.
I propose the wiki creator would create the headsup task and wait for a DBA to decide. The DBA would then update parent task's description, which already has a field for "Shard", saying TBD by default. See T259432 as an example.
What do the DBA think?