I vary. Sometimes I get hard almost instantly; other times, it can take awhile. No telling. It was kind of embarrassing when it happened when I was with a chick for the first time; my cock is super super tiny when soft. Definitely not much for her to work with until it finally came to life. However, once I get hard, I can stay hard forever! Like a little iron spike!
When I was in high school, Frank, one of my best friends, had the biggest cocks in school. He claimed it wsa 9.5 inches; his girlfriend bragged it was 10. I used to sleep over at his house a lot. He had twin beds (his older brother had the other before he went off to college). A couple of times I became aware Frank was jacking off in the next bed. I won't go into details, but I cold tell Frank took forever to get hard. Even longer than I did sometimes! He took an equal amount of time to get off. I could tell by how his covers jerked up and down that he took much much longer strokes than I did. He made gasping sounds when he came. I would jack off silently while he went at it. However, unlike him I'm sure, I only used my thumb and one or two fingers. . . in short, frantic, jerky strokes.