Summarize this article:

Finger limes are ripe when they fall easily from the branch. If you tug at a fruit and it resists coming off, leave it for another week before checking again.   You will notice small white or pale pink flowers in later summer and autumn. These will turn into your finger limes. Don’t pick them, or you will kill off the future fruit.   Ripe fruits won’t fall off the tree, so you will need to pull them off the branches.   The ripe fruits will range anywhere from 1–5 inches (25–127 mm) long. Size doesn’t necessarily indicate ripeness, so if your fruits aren’t growing very long, don’t worry! Prune from April to June, before it begins to flower again. Cultivate an open shape with 4 to 6 branches. Too many branches will make it hard for you to harvest fruit.   Use clean pruning shears and wear gloves to protect your hands from thorns. Cut back excess branches to where they start on the trunk.   Cut each remaining shoot of the tree back to less than half its length. Make the cut just above a leaf. This will keep the tree from getting unwieldy. Temperatures of 10–20 °C (50–68 °F) will keep finger limes fresh. Make sure they are dry before you put them in the refrigerator to reduce risk of rind damage. This is also a great way to have finger limes available to use all year long. Put them in a freezer-safe, resealable bag. Your frozen fruit should be good for 6 months.

Summary:
Pull ripe fruit off the tree from December to May. Prune back the branches after you harvest the fruit. Refrigerate the limes to use them within 3 weeks. Freeze your finger lime fruits whole if you won’t be using them quickly.