We used to do that back in the 1970's! It works but most people are never really satisfied with the results.
You have a lot of better options these days if you want truly wild hair color. They sell temporary hair color in a spray can. This stuff lays on your hair like hairspray and doesn't soak any dye into your hair. You may be able to find this now by asking at a store that sells a lot of Halloween stuff in October. They may still have some in storage. You can find it year round on e-Bay and Amazon and a lot of Gothy-type clothing sites. They also have permanent hair dye in every color at the same sites and probably at your local beauty supply store.
Zero minutes. Why? Because to do that is pretty silly. And it won't work unless your hair is bleached white blonde, nevermind the sticky mess. My advice? Get Manic Panic for a crazy shade or hit Hot Topic for their crazy hair dye selection. While you dye with one of those, drink the kool aid. Just make sure you use gloves & a tint bowl/brush. Good luck!
If you use shampoo on your hair daily, then it will last for approximately 3 months but if you use shampoo on your hair twice a week it may lasts to approximately 6 months. If you are not satisfied with the result, you can wash it with hot water.
Leave it in your hair for about 4-6 hours. I did it to my hair with orange, and I left it in from 8 pm to 3 am (approximately). I had platinum blonde hair at the time and the color stayed for two and a half months, then I got it colored professionally... blue and purple(: