If you're already planning on getting married, then do that before sponsoring him. It's much less hassle. Read through this sponsorship guide:
http://www.cic.gc.ca/english/information/applications/guides/3900ETOC.asp...and gather all the necessary information on your end and have him start on his end. When you do decide to get married, bring all the applications with you to Croatia so that you can fill them out while you're there. Saves you alot of time!
FYI, it's much quicker to sponsor your husband from abroad than within Canada.
Good luck!