IME, the night credits post quite quickly - maybe 1/2 weeks after the CC application was accepted. That said, with rollover nights, you might be better getting them this year, as they would simply rollover to next year, then you would get another night credit on your CC anniversary date. To put in practical terms: say you're at 77 nights this year - 15 bonus nights would put your at 92 nights, 17 of which would rollover. You would then have your bonus nights post next November, meaning that would give you a total of 32 nights for next year without any stays.