I thought the timing belt was an inspection at 100,000km and replacement at 150,000km?
48,000 sounds more like valve clearances to me.
I'm in a similar boat, no service records, and even though the last owner said it was serviced recently, I'm gonna give it a going over before I use it - oil, filters, plugs, brake/clutch fluid, brake pads. So I would say service it now, so you know it is done.
A few thousand kms early won't make much difference IMHO. If you are worried about extending the gap to the next service interval, I would just slip in an oil/filter change somewhere in between, then get back on track at the next service.
Better to service too often than not enough!