I came from CS1000 as well. As a matter of fact, we still have the CS1000 running alongside the CM as we are converting over. I am good with vectors, VDNs, and have an okay understanding of signaling groups, trunk groups, route patterns, etc... I am still learning the command structure like when to use list versus display and all that. My lacking knowledge would be the more technical stuff like security certificates, call tracing, best starting point for troubleshooting various issues, ESS, what phones use what media server, what gateway, etc...
I am slowly getting there.