As a 28 year old male am I at a good age to start a baby aspirin regimen?

You should talk to your doctor about it. I would say it depends on more than just your current health. The doctor would also consider your past medical history and your family history to decide if it would be beneficial at this time.

Perhaps a big boy aspirin regimen; as in full size aspirin?

I’d talk to a doctor. NSAIDS taken regularly can cause stomach ulcers, so I don’t know that the benefits necessarily outweigh the risks, unless you think you have good reason to think you should be taking it.