Here's a general guideline:
1. 87 Octane Fuel: 8 to 10 degrees before top dead center (BTDC)
2. 91 Octane Fuel: 12 to 14 degrees BTDC
3. Premium/93 Octane Fuel: 14 to 16 degrees BTDC
Again, these values can vary, and it's important to consult the vehicle's specific manual for accurate ignition timing settings. Also, the ignition timing can sometimes be adjusted based on performance factors, such as using modifications or racing components, but those changes are typically made by automotive professionals.