I've used them for so long I don't remember but I don't think it took very long. I do think I had a harder time with bifocals than mono-vision. I did only use monovision for work and used my distance lenses for cycling, (especially mtn biking) skiing, driving at night. I now have mono vision bifocal lenses and they work great except for driving in the rain and nighttime driving.

Try wearing them when you're not using the computer. I also think I adjust my distance from the computer when I'm using the contacts vs. glasses.