I had 10 minutes to get a Suica-NEX recently and that was not enough time. The travel center has become a nightmare. American and chinese tourists will spend half an hour at the counter asking questions. Last fall, I arrived and saw 3-4 people in line at the travel center with 3 staff. I had 30 minutes to get the ticket, since I emerged from customs right at :15 or :45, and it took me 20 minutes to get the Suica-NEX. During this time an old caucasian woman had tied up one staff member for 20+ minutes asking questions about trip planning.

So, two weeks ago, at the regular ticket counter near the turnstile, the line was also moving slowly. So I aborted and went to the automated machines, which does not allow Suica-Nex purchase. I managed to get on the train with seconds to spare. Next time, I think I'll take the bus........

If you have JR pass then you have to go to the travel center.

p.s. I have tried to refill a Suica card with my Japanese CC (citi) but was rejected after trying to enter a pin. I guess, I know why now.