Best practices for integrating C4C with on-prem ECC

HI all

are there any best practice docs/guidelines for integrating c4c with an on-prem ecc system at the beginning of a project rather than integrating sometime later? (Which is the path were headed down just to get a live c4c system up quickly) I belive it will be better to have the integration right at the beginning even for a simple customer id so then we wouldnt  have to do rework later. any articles , docs would be helpful so I can build a case

thanks in advance