I don't have a set time either, just whenever I look at their feet or they claw me to death which ever comes first. Usually about once a month.

Katie doesn't like it but all she does is try to pull her feet away.

Bull will show those cute lil teefers of his and when he sees that I'm not scared just tries to pull his foot away.

Duke has only had his done twice so he still doesn't like it but I can still hold him in one hand and cut with the other so he has to resort to whinning.

Both Katie and Bull's nails are black (unless I decide to paint them ) so it's a guessing game. Duke on the other hand is white so I can see the quick.