NZ签证停留期和有效期疑问？

请问NZ签证“三个月内入境，可停留一个月的签证” 停留期要在签证有效期的三个月之内吗？停留期一个月又是指的30天？还是31天呢？例如我的签证有效期是8.27-11.27，但我想买11.15-12.15的机票可以吗？
Start Date：27/Aug/2013 First entry before: N/A Number of Entries: Single Expiry date travel: 27/Nov/2013 Visa expiry: See Conditions Conditions: This visa expires 1 month(s) after first arrival. When entering NZ, stay is subject to grant of enter permission. You must leave NZ before the expiry of your visa or face deportation.