My first times were fun ... no worries/apprehension at all. Years ago CGC was actually very different. It was more like the prize in a box of Cracker Jacks ... you don't know what you're going to get, but you know it's going to be good. Nowadays, it's more like gambling ... could be good, could be bad. Back in the day, the first thing you looked at was the grade. These days (or at least the latter days of my submitting), the first thing you look at is the condition of the slab/comic.
You should be ok, though. The odds have definitely changed, but they're still in your favor.
I feel bad for first-timers today. They missed out on when slabbing your comics was fun and care-free.