How long to wait to use ammonia after using bleach?

I typically use a very diluted bleach/water (food safe grade) mix around the house for disinfectant. Sometimes I'll maybe dump a cup in the toliet or in with the wash but no more than once a week. Lately I've been hearing great things about ammonia for spot remover, oven cleaner, blah blah blah and of course, you don't want ammonia anywhere near bleach but now I'm wondering since I have a septic tank wouldn't they end up mixing in there? That's no good either, right? So how long would be long enough in between switching cleansers? (Actually I'm using neither right now since I'm pregnant-just a magic eraser and some patience and maybe a little vinegar) AND is ammonia as corrosive to metals as bleach is? Any advice will help, thanks!