everyone deserves a second chance to change their username
Why are you only allowed to change your username once?

You could just choose a username you are happy with to start with, then you don't need to change it!
what if you change your mind eventually

You can change your username avery 90 days. If you want to change it urgently, you may contact chess.com memeber support and you'll receive a response in about three days.

You can change your username avery 90 days. If you want to change it urgently, you may contact chess.com memeber support and you'll receive a response in about three days.
this post is almost 5 years old buddy.
Yeah, I think the primary reason for the one time change rule is probably because now that everyone has VPNs, the only way for them to ban you if you were abusing is with your username since they can't get your real IP anymore, so if you could change it at will, you could threaten an act of terrorism against someone and then just change your username and get off scot free, though I imagine they probably keep a record of changing usernames, but it's probably just to prevent a giant pain in the neck for the mods.
so turns out it takes around 3 days depending on how busy the support team is