Hi Dingle!
Reading Rohloff Stories (the company publication telling all about the Rohloff hub, its development, and the human stories behind the users and service), I've come to think the first service is likely the most important.
Why?
While it appears the oil itself doesn't break down, it does serve as a suspension for the small metal particles that accumulate due to wear. Also, if water has somehow managed to get in the hub, changing the oil will take the water out with it. There is a story in the book of a hub that was somehow used for an extended period with nothing but the assembly lube (apparently the original owner had not filled it per instructions). It was sent in eventually, but too late to prevent damage. Rohloff said if it had even been sent in at the end of the first year, no damage would have occurred from running only the assembly lube.
Too, wear tends to be highest on a new hub as the parts begin to mesh and wear to each other. That first oil change removes the problem before they can cause rough or imprecise shifting. It seems many cases of rough Rohloff shiftng are speedily resolved with only an oil change. Subsequent oil changes probably aren't as critical due to the lessened rate of wear, but I would still consider them wise and i plan to keep to schedule myself.
Given your low mileage, I'm virtually certain the hub would be okay without an oil change, but given the cost of the hub, why risk it? Once changed and refilled, you'll have no more worries till the next service internal. I picked up a spare oil change kit off eBay for only USD$22, so the cost isn't terribly high. I normally buy from SJS Cycles, but grabbed this one because of time and because the vendor was nearby so arrival would be almost immediate. I'm not sure how common they are at that price.
So, all told, I think it's a good precautionary measure to make that first oil change now and avoid worries and inconvenience on down the road -- and then do regular changes thereafter.
Hope this helps.
Best,
Dan. (...who believes regular engine oil changes for the car are cheap insurance, too)