More or less I kind of figured it out on my own. I use the following powershell script to just rename the user after it gets created in 365.
Import-Module MSOnline
$o365ObjectIdBinary = $Context.TargetObject.Get("adm-O365ObjectId")
$o365ObjectId = New-Object "System.Guid" @(,$o365ObjectIdBinary)
Set-MsolUserPrincipalName -ObjectId $o365ObjectId -NewUserPrincipalName "%mail%"