JR Rail pass query

Ive bought a voucher for a 7-day JR rail pass. I arrive in Japan on 18th January, but I intended to use the pass from 23-29 Jan, most importantly from a return Shinkansen trip between Kyoto and Tokyo.

At what point in my trip should I trade in my voucher for the pass and make the reservation on the Shinkansen? Can I do it on arrival at the airport on the 18th? Or do I have to wait til the 23rd? Thanks for your help!

You can do it at the airport. Just tell the station staff that you want to use the pass from 23rd.

Thanks...its possible though I might have to change my plans and not use the JR Pass...I bought it from JTB UK...are refunds possible?

The refund policy should be stated with whoever you purchased it from. For example when I purchased my JR Pass voucher from Kintetsu were that I refund it back through the office that issued it, and there was a minus 10% on the refund.

As for if you kept the JR pass, yes on the form when you exchange the voucher for the pass, the form will ask which date you will like to start using it.