TCP Traffic Path Diagram

I have a question specifically regarding after a decision has been made to send a packet to be snatted or routed. If I leave the SNAT setting on my VIP as auto-map I know that the routing and forwarding from there on uses the self-IP of the vlan that is used in the static route. If I have a SNAT Pool implemented is there a decision that is made before the traffic is sent to the routing table? I am new to SNAT Pools. any help you can provide is greatly appreciated.