Webhook to Create table AND copy records into new table

You are correct that you wont be able to add records to a table that doesn't have a dbid yet.

But you could guess what it should be.  If your table is going to be called August 2017, then the text version of the dbid would be [_AUGUST_2017]

The BIG question here is, why are you creating a new table for every month?  That does not sound like a good solution.