picking up pass/activating

Hi

I purchased the 21 day pass although I am wondering when I should get it activated.

I fly into Haneda at 3:25pm and then get on my connecting flight at 7pm to Osaka Itami. Would it be a good idea to get my pass activated at Haneda before getting on my second flight? Online, it looks like the other location for activation is at Osaka International Airport, which is 1 hr from Itami.

Is activation in Haneda in a location convenient to pickup? or will I have to leave the airport and re-enter?

thank you
heather