Usernames must start with a letter? That is an odd requirement. I usually pad my username with zeroes when sites dont let me choose dfc. Out of curiosity why the constraint?
Databases are usually sharded by the first letter of the username. Devs like to start their usernames with a number, which causes problems. Also, usernames are injected into their code. Therefore they must be valid identifiers. Don't name yourself exit() or ret, or you'll crash their servers. Naming yourself nop will give you a distinct advantage relative to other players, however. I don't know.
It took me too long to realize you weren't serious