case approved and received I-129

My case got approved and employer received the i-129 form on Feb -2016. Now I am not able to attend VISA interview due to some personal reasons. now i would like to know how many day we will have chance to attend interview? is there any expiry date for this or any time we can go for interview??

Please let me know your thoughts regarding the same.

Many thanks in advance!

You can attend interview anytime during petition validity period. Whenever you appear for stamping, make sure you have recently dated documents.