Activation Rail Pass

Hello,

I was wondering if it is possible to activate the pass but use it a week later.

I will be going to Japan for 4 weeks, my family joining me the last 3 of them. I will go to Mastumoto, where I'll meet with some friends of mine in the first week. I would like to use the railpass on the 22th of July to travel from Matsumoto to Tokyo. However, there seems to be no activation place for the pass in Mastumoto. I will be traveling from the 22th of July to the 11th of August, so it is not possible for me to activate the pass earlier. Is it possible to activate the pass in Nagano between the 17th and 19th of July, but let the starting date be the 22th?

Thank you in advance,
Tanja