When to request production of documents

There is no limit on the number of documents you can request so long as they otherwise follow the discovery rules (request discoverable information, are not burdensome, oppressive, harassing, etc.) You can serve discovery in any order you choose.

often all of the initial written discovery is served at one time. follow up written discovery can be served if necessary.

There is no order to discovery. You may propound discovery in any order you deem appropriate. Yes, you can propound multiple requests for the production of documents. If this is a limited civil case you need to be aware of the "Rule of 35" pursuant to Code of Civil Procedure sections 94 & 95. If unlimited, a declaration is required if special ROGs or RFAs exceed 35.