Just got the below partner email from the Nats. It looks like the cards are not getting here in time for Opening Day.
Dear XX:
We are so excited to kick off the 2015 season! Your 2015 NATS PLUS Partner Card(s) have been printed and are being shipped. We apologize for the delay. Please be on the lookout for an email containing your tracking information, as your NATS PLUS Membership Package will be delivered within the next several days.
As part of our digital ticketing and environmental sustainability initiatives, your package will contain your NATS PLUS Partner card(s).
If your primary account holder has sent you seats for the Exhibition or Opening Day game(s), in the unlikely event that you do not receive your cards before those games, we recommend that you print your game tickets via your online Access account.
In order to print your game tickets, please email them to yourself by completing the following steps.
TO EMAIL/PRINT A SEAT:
1) Log in to your online Access account.
2) On your NATS PLUS account homepage, click MY GAMES on the left navigation menu.
3) Select EMAIL SEATS.
4) From the drop down menu, select the game you would like to email.
5) Enter the name and email address of the intended recipients.
6) Check the box next to the seat you would like to email and the information will auto-populate.
7) To send the seat, hit TRANSFER.

You will receive an email from access@nationals.com.
9) Open and print the pdf files that are attached.
IMPORTANT PACKAGE INFORMATION
1) Your NATS PLUS Membership Package contains your NATS PLUS Partner card(s)
2) Pull the right side of the package (with the labeled arrow) to reveal your card(s)
If you have any questions regarding your account, please contact your Nationals Account Representative directly. You may also contact the Nationals Ticket Sales and Services Department by calling 202.675.NATS(6287) or via email at stcomments@nationals.com.
Sincerely,
Washington Nationals Ticket Sales and Services Departmen