Options for activation

Greetings all.
I will be traveling from Niseko to AppiKogen on Jan 18th and was hoping to activate my 21 day pass on the same day. I checked the link below and the closest station to activate is Sapporo; however, this causes me to backtrack quite a bit (plus paying for train from Niseko to Sapporo). I was hoping to exchange the voucher when I travel through Sapporo a week before I get to Niseko (I'll be in Niseko for 10 days, so don't want to activate it until I leave) and have it active from Jan 18th on.

Is there anyway to exchange my JR Pass voucher a week before it becomes active? Or does exchange the voucher start the activation clock?
Thanks in advance.

https://www.jrpass.com/blog/where-to-exchange-the-japan-rail-pass