In my experience, customs for non-Korean citizen at ICN is always relatively quick (and not bad for Koreans either...my husband is usually out not too long after me). Once you get on the KAL limo bus, it will take you a little over an hour (maybe 80-90 minutes if you run into really bad traffic). There is a bus at 7:35 (also one at 7:10, but I dont think you'll make that one). So assuming you make the 7:35 bus, if there is a lot of traffic, you'd get to your hotel right at 9, or a few minutes before. If there is no traffic, the earliest you'd be there is 8:40-8:45.