Set specific username format

Hello,

I like to set specific username format. I want the username be firstnae.lastname so when a new user register, once he/she enter the first name and lastname. The username field should be populated with this info in the format firstname.lastname.
Is this possible and how if it is?

Thanks

Set the username field to not be on registration within CB > Field Management and it'll now auto populate with the Name, but it'll be separated by a space. I suppose you can set name format within CB to use a single name field then set custom validation on the Name field.