For me, I would get the bracelet. Here is why and some other thoughts...
If you get a bracelet, you will personally be able to see it and stare at it all day. Remember that ear to ear grin? Yup... with a bracelet, it's going to be a permanent ear to ear grin. I'm a ring person, and I stare at my rings often. My husband will see me doing that and will say "I see you staring at your bling again."
Which brings me to the necklace...
A necklace, especially a short pendant, is great for others to see. You will smile when you put it on, but after that, you can't see it, hence you will not really be able to enjoy you first VCA piece (unless you see yourself on Zoom all day

).
So, how to decide... bracelet or necklace...
Think about if you want this piece to look at and enjoy for yourself, or if you want this piece to show others you have a VCA (for the few people that even know about VCA). It's a subtle difference, but how you answer that question may help you decide.
For me, I buy jewelry for me, so no doubt in my mind, I would get the bracelet, especially as a first piece. I will be able to stare at it and see its beauty. You can get the pendant later to add to your growing collection (birthdays come every year!


)
I see you like Sweet and you like RG, so it's between the hammered RG or Carnelian.
The hammered RG bracelet is safe and worry free. However, to me, safe is also a bit boring in this case. Why? The Sweet bracelet is very dainty, and I think with an all metal RG chain and metal RG motif, the motif will get a bit lost. There is no contrast; it will just look like a chain. The carnelian, however, will pop. You can't miss it, a little pop of red! Both pieces will match with all your outfits. Red is a neutral, it goes with most everything. It's a happy neutral. Hence, of the two, I would get the carnelian. That's just me though, and it's all preference.
If you think you can love YG and MOP, this combo would be my first choice. I love the YG and MOP combination. It's the bomb, and the MOP will make your skin glow. Plus, YG and MOP really goes with everything. This is the bracelet I am thinking of in case you might be interested:
Sweet Alhambra bracelet Yellow gold, Mother-of-pearl- Van Cleef & Arpels (vancleefarpels.com)
I do want to point out with the Sweet bracelet, as there is only one motif, it will drop to the bottom when you wear it. It's natural due to the weight of the motif vs. the chain. You can shorten your bracelet tight so it doesn't move as much, but then you will need help putting it on and taking it off which may prevent you from wearing it often. For me, I would stay with a looser fit but just know gravity will take the motif to the bottom every now and then. It's different than the 5 motif which has motifs all around the bracelet, hence the weight is distributed evenly. Just FYI in case you did not think about this minor point.
I am so excited for you, and I think you will love your first VCA, whichever piece you choose. All VCA is so beautiful, and you cannot go wrong with any piece.
Just my two cents to help you decide. I hope this was helpful.
And... an early Happy Birthday to you!