Box dye help!

So I get grey hair like crazy even though I'm not even 30 yet. I decided to dye my hair soft black (my natural color) just to cover them. While I was looking at the hair dyes I saw this beautiful teal color that actually works on dark hair but my hubby probably wouldn't have been too happy with me spending $15 on hair dye. Turns out he would've been fine with it but I've already dyed my hair black. Can I put the teal over the black? Would it show up as well? Should I wait a while before I dye it again? Yes, I know box dye is a no no but I don't have the money for a professional and I get bored with my hair too much to spend $100+ on that. Lol