Starting a network- Multi Database, Anti-Sblog

In setting up a new network, what is the BEST approach, when it comes to Multi-DB, Anti-Sblog, set up and configuring.

I was reading instructions for Anti-Sblog and it recommends

----------------------------------------
If you are using Multi-DB:

You need to add the global table lines to db-config.php BEFORE installing Anti-Splog plugin or running the sql.txt
Add this line to your db-config.php if using multi-db:

add_global_table('ust');
-----------------------------------------
What happens IF you add the databases later?

If one is expecting to grow the site, should one go ahead and add multiple databases right at the start?

There should be a step by step flow chart of what one should do for set up of a new site. I know there is a lot of help and instruction, but this should be a part.

So, what should I do?

How many DB's should I have? What if MORE are needed later?

Thanks,
Tom