As an aside,
My ears are stretched, semi-large (7/16). They don't go completely back small enough to wear most regular earrings, but they do go small enough that they aren't noticeable, and they do go back rather fast (within a couple weeks).
Also, if I take them out for a while and then decide to put them back in, they stretch pretty quickly-- I can get them from start to 10mm in about 6 weeks.
If you're stretching for the first time, it can take a very long time (if you are stretching the right way and purposely avoiding blowouts)-- it can take a year or longer. Of course, there are people who just jam them through and end up with blown out, skinny, cat butt ears as well, but even then, it takes some time.
Lots depends of the elasticity of your ears, and whether they have been stretched or not before.
ETA: there are also flesh coloured plugs that lots of people who work in conservative workplaces wear, and those sometimes can blend in so well that unless you are specifically looking for it, you won't notice.
This has been your ear stretching primer for those of you who are unfamiliar