Which will take effect quicker? Drinking a cup of instant coffee or eating raw powdered coffee?
If you want the effects of the caffeine to be felt the most quickly, you probably should buy caffeine powder or pills, be careful though that you could easily overdose yourself to death with the caffeine powder or if you took more pills than recommended.
Though, if you don't want to buy the isolated caffeine, drinking it would probably be quicker, since otherwise you'd lose the effect of the absorption by the mouth (which is faster because it goes straight into the bloodstream), and you'd still have to digest the powder to get to the caffeine.
Caffeine overdose is a real thing and one should be very careful, especially with caffeine pills.
That being said, if you want to feel the effect of caffeine as soon as possible and that was your only goal, snorting would be the fastest, although it would feel disgustingly sticky and burn.
If you want to do it by ingestion, your best bet is to avoid as much non-caffeine stuff as possible - use pills instead of coffee, don't put extra sugar or milk in the coffee.