Uh, only if invited? I mean do you not ever get lunch with coworkers or invite them to events you're hosting or ask if they want to see a movie or concert with you that you've been into? The important thing is to establish a positive social relationship before indicating any sort of sexual interest, so they know you as "My chill coworker John" rather than "John the guy at the office who's always staring at my tits and asked me out for 'drinks' before we ever had a single conversation." It's not impossible to establish sexual or romantic chemistry before establishing social chemistry, but it's sure harder.
I was wondering if someone would jump on that. Are you genuinely curious about or unclear on the difference? Do you legitimately not understand how those two statements can be true? I'm willing to try to explain, if you're seriously interested, but if you're motivated by trying to demonstrate that I'm incorrect I won't waste my time.