Is it normal to blank out on the test and still pass?

That feeling of walking out sure you failed is basially a rite of passage. I missed more than you did and still passed, so you're in good shape.

Once your call sign shows up in the database, usually within a few business days, you can legally get on the air. Before that, you can absolutely listen, and I'd recommend it anyway. Find the local repeater frequencies, they're often listed by the local club or in a repeater directory, and just monitor for a few days. You'll hear how people talk, how they announce themselves, and what the general tone is. Every repeater has its own personality. Some are chatty and welcoming, some are quiet, a few have grumpy regulars.

When you're ready to transmit, the etiquette is simple. Listen first to make sure nobody's mid-conversation, then key up and say something like your call sign followed by 'listening' or 'monitoring.' If someone responds, identify with your call sign, be honest that you're new, and don't apologize for it. Most hams love helping a newcomer and will happily chat with a first-time caller. The main mistakes beginners make are talking over an ongoing QSO because they didn't listen first, or kerchunking the repeater, meaning keying it without saying anything. People notice that and it drives some of them nuts.

On the fraud feeling: everyone has it. The test proves you know enough to not interfere with anyone, not that you know how to operate. That part comes from doing. Half of what I crammed for the exam fell out of my head within a month and it never mattered, because the stuff you actually use on the air sticks naturally. You'll learn more in ten real contacts than in another week of study.

One practical tip: program a handful of local repeaters into your radio before you even get the call sign, so the day it pops in the database you can just go. And check if a local club does a weekly new operator net or a ham breakfast. Showing up in person is the fastest way to stop feeling like an outsider.

Congrats on passing. Don't sweat the memory thing either, my first few contacts were pure nervous babble and nobody cared. One thing I'd add: see if there's a weekly net in your area. Checking in on a net is way easier than keying up random strangers, since there's a structure and someone always acknowledges you. That's how I got my feet wet. Also grab a spare battery or two if your handheld uses a proprietary pack, they seem to die at the worst moment.

The gap between passing and knowing shrinks faster than you think. I've been on the air 19 years now and my very first contact was me fumbling through a net check-in with my hands shaking. Nobody remembers your rough start except you. One thing I'd add to the repeater advice: figure out the offset and tone requirements for your local machines before your call sign lands, because that trips up more new ops than etiquette ever does. The club's website or a member will sort you out in five minutes. And once you're comfortable on voice, start poking at where you want to go next, wheather that's a General ticket, digital modes, or somethig else entirely. The license is a door, not a ceiling.

Update: call sign finally showed up in the database and I listened to the local repeater for a few evenings like some of you suggested. Found a weekly net and checked in tonight with shaking hands, exactly like predicted. It went fine. Still stuck on programming the offset into this handheld though. Is there an easy way to tell if my signal acutally made it in when nobody answers?