I have 1 node right now, that I need to create a 'RAC-able' database on-Instance 1. After a month, I will get the 2nd node, which will have the Instace 2 of the database.

What should I set his parameter to now ( 1 or 2) to create the database ?
CLUSTER_DATABASE_INSTANCES

I am guessing 1, and as the increase, I can increase this parameter also ? Is this tight ?