Depends, self diagnosing seems extremely challenging and introduces doubts and bias so it can't be 100% accurate. Which an outside perspective can help with.
I've done [insert] my whole life so it's normal.
I found out [insert] isn't normal and common in autism.
I look into autism. Oh but I don't do all those other things.
Maybe me doing [Insert] is just me being weird but I don't have autism!
After a few weeks I find out another [insert] that I do is also common in autism. Cycle repeats.