How often are there foster kittens in a shelter?

[asherbeexo]

I just filled out my application and am a offical foster parent. The only thing is though. There are no kittens =[. I was wondering if any one knew how often they get kittens in? The coordinator said she has been getting them in once a week; do you think thats true? Also when does litters start to pick up; in March?

Thanks in Advance!