Hi ya mate.
Firstly, i would not bother with wrist curls - perhaps just my opinion, but if you do other kinds of forearm/grip/wrist related work, they are pretty poor in comparison.
This would depend on your routine as a whole quite a bit, because what you do in your routine would affect how you should divide the exercises. For instance, doing barbell holds (or lockouts, or whatever they are called), farmers walks and such like after a deadlift day is not wise
But you could do something like plate curls even straight after deadlifts in my experience.
I've never had a good solid grip routine, always just done this and that whenever, so i can't really give any good advice. Also, grip recovery seems to be more individual than other kinds of recoveries and some people can do loads without burning out. grip training involves relativesly small muscles so it is unlikely that they would contribute greatly to overtraining on your body as a whole. Having said that, keep a close eye on how your hands and forearms are doing because pretty much every new grip strength trainers tend to overdo it and end up with sore arms for a while