About five minutes.

No, seriously...your mint will very rapidly regrow new terminal leaves plus a few more for good measure. Pinching and pruning always creates more growth than we removed.

It depends on what planting zone you are in, the watering, and everything, but it will grow fairly quickly. Just make sure to leave about two thirds of the plant.

Undoubtedly someone will say that you can cut more than 1/3 off - they usually do when I say to leave 2/3's of the plant. Leaving 2/3's of the living plant is the rule of thumb for pruning and herb harvesting. Mint will survive a harder cutting than 1/3 off, but it will take it longer to bounce back and regrow enough for you to harvest from again.

You're doing the right thing. Start small and slow with your harvesting. You'll get the feel pretty quickly as to how much you can take and how your plant will respond. And if you start slowly in regards to harvesting, you can learn without any of those, "oh, I shouldn't have done that" moments.

FataMorgana

Yes. I'm picking slowly. Just enough for a cup of tea of two at a time and not very often. When mint regrows back, it doesn't grow back in the same place you cut it, does it? Because I notice that its not growing back where I cut it but it may be growing new leaves off the sides of where I cut.

You got it. That is how plants grow back.

FataMorgana

Thanks for all the info. I'm obviously a newbie at gardening. =)