thanks everyone for your replies!

I can't leave food just lying around for them because my cat Amelie is a little piggy and would do nothing else but eat all day. As it is, I have to make sure to put Nino's food bowl on the fridge when he is done eating so that Amelie doesn't come in and eat his food.

I did the treats things for a while, then I had cats breaking into the treat cabinet and ripping the bag of treats apart, they can be very naughty sometimes!

Anyways, it's nice to know that I would be reinforcing their habits, so I'll just stick it through Amelie's "feed me" period.

Again, thanks for the advice!