give it a lot of time and thought, it's your only chance to change. consider what you actually prioritize in a username, thinking about whether you like how it sounds to you, whether it's easy/convenient in some way, or maybe you just like the ideas it brings to mind
preferably, wait until a friend or someone around the forums or elsewhere in the community gifts you a supporter tag
that will give you a lot of opportunity to refine what you're looking for. don't rush it, let yourself enjoy a name that's intuitive to you and feels right for who you are or what you want to represent yourself with
i would have hoped to tell myself the same thing. i didn't really think it through, usernames were never easy for me, and ultimately i didn't really give myself the time to see whether i actually even liked what i left myself with
the only way for any of it to change is to pay money i don't have, as minimal a price as $8 might appear to be...