What should i fill in 'Date of Use'?

Hi, I'm going to buy JR East-South Hokkaido Rail Pass for me to use on 17th February 2025

I'm going to arrive at japan on 4th February, and planning to exchange the pass on that day and get the shinkansen reserved seat for my trip to sapporo.

What should i fill in the 'Date of Use', should i fill it 17th February (my activation date) or 4th February (arrival date).
If i fill with 17th February, can i book the reserved seat on the 4th february?

Thank you!