You absolutely MUST consult your vehicle's repair manual. This manual will provide the correct specifications for your specific engine and year. These specifications are usually found in the engine specifications section or the ignition system section.
Attempting to set the timing without the correct specifications from your vehicle's repair manual can seriously damage the engine.
Instead of guessing, find a reliable repair manual (Haynes or Chilton are popular options) or use online resources that specifically detail the procedures for your exact engine. Improper timing can lead to poor performance, engine damage, and even catastrophic failure.