Hi, ako naman I changed my last name na para walang hassle sa immigration papers/processing. It took me a while lang talaga to file. June ang wedding then November pa ako nag-file. August naman ako nakapagparenew ng passport, I waited pa kasi doon sa MC. Then almost a month bago ako nakapagpa-sched sa DFA dahil laging puno. Then I changed all my IDs na rin including PRC na narelease after 2 months.. Imagine.. October na nung narelease PRC license ko.

Hehe. Anyway, it's up to you kung ayaw niyo na magpalit ng last name kasi sobrang hassle, I swear. Just make sure lang na valid ang passport niya for up to 18 months (I think? Correct me if I'm wrong here, kasi 12 months ang maximum processing time + 6 months validity kapag nagtravel ka).
About sa Marriage Certificate naman, makukuha mo siya after 3-4 weeks after the wedding kung may advanced endorsement. Then get na rin kayo ng Advisory on Marriages (AOM) niyo (Sponsor at PA).