D. Rex
Magic Eight Ball
I got the whole leveling with base class bit.no, you will get an ASI at level 4 then at level 8, and 12, and so one and so forth(as that is how your base class works, every 4 levels), but you ignore any ASI's from classes.
Chuckles is correct, your ASI is tied to your character's level (which is tied to the class you chose first). You'll get hella strong faster, but it will mean you don't always get something when you do level.
But when you said getting ASI at four I though you were meaning extra.
Though what about the fighter class? It gets an ASI more often than every 4 levels?