How often should you get your eyebrows threaded?

[bunnie1975]

Not sure if its when they start to look like they need it or if its should be done after a set time? Don't want o over or under do it x

Every 4-5 weeks x

I get mine done when they need it, and it tends to be longer the second time around. E.g. the first time, need doing after 4 weeks - next time, I can leave them 6 weeks