How long does the effect of nasolabial fold Botox last? How long should I wait before getting it again?

As I get older, my wrinkles are getting more numerous and deeper. Other wrinkles aren't that noticeable, but one day when I looked in the mirror, my nasolabial folds were so prominent that it made me look much older.

So, I'm thinking about getting Botox. However, if I start getting it, it seems like I'll have to manage it by getting it periodically and repeatedly, so I became curious about how long the effects would last after just one injection.

If I get Botox for nasolabial folds, how long does the effect last after a single injection? How long should I wait before getting another injection?