At 12,056 this past weekend, it came up with the A 0 1 service due in 4 weeks prompt. That would suggest 13-14k miles for the 2nd servicing if mileage based. But the 4 weeks puts the timing exactly 6 months after the first servicing. If mileage based, I would have expected it to request it at 15k. I lost a month of driving the Clarity due to having to use a truck due to cargo. So, now I'm thinking it is more time based.
I'd definitely go for the free service and hold onto the supplies. You will eventually be able to use those. Might as well save the cash for now. Just be aware they may use this as an opportunity to sell extra services.
I'm tempted to just do the rotation and see what it says regarding the oil change. But, it wasn't hard to do, so I will probably go ahead with the oil too.