A 12" sink is already pretty tiny. The inside dimensions are around 8". You can't fit a stock pot in that. Or a colander. And you need a 15" cabinet for it. I personally would prefer a 20" sink in at least a 24" cabinet.

It's our second sink and I'm really only going to use it for filtered drinking water and maybe washing fruit and vegetables on occasion. Wouldn't put a stock pot in it but if I need a 15" cabinet even with a smaller sink then I may as well stick with what I have.

You do realize you can cheat here....
Depending on what is on either side of it, you can cut the sides in a bit.
Going left to right we have a full size dishwasher, a 15 inch bar fridge, a 14 inch sink (in a 12 inch base cabinet... :), a 15 inch ice maker, and a 24 inch wine tower.
And a coffee maker and cup warmer above the dishwasher.....
Yes, its a bit much, but its how I keep my party goers out of my cooking space.

And be careful that you size a faucet appropriately with the sink. If its really powerful (like a real kitchen faucet), it might splash a lot. If you wash your hands or glassware in it, it will also splash a lot onto counter if small. A bar sink is best for dumping old drinks into or for filling containers with water....

Cutting the sides of the cabinet effictively permanitizes the sink choice. And, it compromises the support of the stone counters above. I do NOT recommend doing that. In the picture shown above I would want additional horizontal stringers connecting the ledgers front to back to increase the stiffness of the support. Wood bends. Granite doesn't. That can equal cracking if someone leans on that just right.