Gold Xbox Live 12 month

Xbox one question. I have Gold Xbox Live status. Expiry date of my status is June 2015. Can I buy a new card and activate it later? In June or December? Is there any restrictions to activate existing card (expiration date, validity date)? Or ... Maybe I
can activate it right now and expiry date will extend ( to June 2016 )

Thanks

:)

 

1 year Xbox Live Gold - $36

xbox live 12 months gold subscription card gold pl eu us for 33$ (PL/EU/US)
Xbox Live - Buy 12 Months GOLD Subscription Card (Global)

 

Xbox One Live 12 Months ??

MS Store US says

Day One 12-Month Xbox Live Gold Membership - Microsoft Store

Day One 12-Month Xbox Live Gold Membership

For a limited time, get a Day One 12-month Xbox Live Gold membership and play Killer Instinct: Round One, with the exclusive Shadow Jago character. Includes commemorative card and case.

 

From what I remember to the best of my ability, you can have up to 36 months of gold time on a gamertag and that the membership term that you are looking to redeem will kick in once your current membership term expires. It's up to you if you want to go ahead
with adding a year of gold to your account or if you want to wait near the expiration date.

Regarding codes, unless otherwise stated on the card or with the code, you can buy some prepaid gift cards and redeem them at a later time. With that in mind, you can go ahead and buy the 12 month gold membership gift card and redeem it when you want to.